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Array Algorithms
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‎arrays/binarySearch.go

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/*
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// Binary Search in an array of a given size
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// Prints if a given number is found in a sorted array and prints the index of the number if it is found
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*/
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package main
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import ("fmt"
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//"reflect"
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)
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// Binary Search Iterative
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func BinarySearchIterative(array *[]int,startIdx int,endIdx int, searchNum int) int {
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arr := *array
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var returnVal int
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fmt.Println("Using the iterative Binary Search approach")
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for (true) {
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mid := startIdx + (endIdx - startIdx)/2
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if (endIdx<startIdx) {
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//fmt.Println("Element not found")
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returnVal := -1
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return returnVal
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} else if arr[mid] == searchNum {
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//fmt.Println("Element found at index:",mid)
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returnVal := mid
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return returnVal
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} else if arr[mid] > searchNum {
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endIdx = mid-1
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} else {
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startIdx = mid+1
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}
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}
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return returnVal
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}
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// Binary Search Recursive algorithm
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func BinarySearchRecursive(array *[]int,startIdx int,endIdx int, searchNum int) int {
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arr := *array
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var returnVal int
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//fmt.Println("Using the recursive Binary Search approach")
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mid := startIdx + (endIdx - startIdx)/2
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if (endIdx<startIdx) {
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//fmt.Println("Element not found")
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returnVal = -1
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return returnVal
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} else if (arr[mid] == searchNum) {
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//fmt.Println("Element found at Index:",mid)
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returnVal = mid
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return returnVal
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} else if (arr[mid] > searchNum) {
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returnVal = BinarySearchRecursive(array,startIdx,mid-1,searchNum)
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} else {
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returnVal = BinarySearchRecursive(array,mid+1,endIdx,searchNum)
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}
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return returnVal
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}
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// Unit Test for Binary Search
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func main(){
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/*
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var length,searchNum int
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fmt.Println("Enter the size of the array")
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fmt.Scanf("%d",&length)
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fmt.Println("Enter the ascending order of array elements seperated by a space")
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arr := make([]int,length)
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for i:=0;i<length;i++ {
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fmt.Scanln(&arr[i])
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}
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fmt.Println("Enter the number to search in the array")
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fmt.Scanf("%d",&searchNum)
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fmt.Println("Array:",arr)
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*/
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arr := []int{1,10,20,47,59,63,75,88,99,107,120,133,155,162,176,188,199,200,210,222}
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searchNum := 155 //Solution is 12
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//search Num := 75 //Solution is 6
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index1 := BinarySearchIterative(&arr,0,len(arr)-1,searchNum)
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fmt.Println("Number found at index:",index1)
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fmt.Println("Using the recursive Binary Search approach")
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index1 = BinarySearchRecursive(&arr,0,len(arr)-1,searchNum)
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fmt.Println("Number found at index:",index1)
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}

‎arrays/binarySearch/binarySearch.go

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/*
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// Binary Search in an array of a given size
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// Prints if a given number is found in a sorted array and prints the index of the number if it is found
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*/
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package binarySearch
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import ("fmt"
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//"reflect"
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)
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// Binary Search Iterative
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func BinarySearchIterative(array *[]int,startIdx int,endIdx int, searchNum int) int {
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arr := *array
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var returnVal int
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//fmt.Println("Using the iterative Binary Search approach")
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for (true) {
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mid := startIdx + (endIdx - startIdx)/2
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if (endIdx<startIdx) {
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//fmt.Println("Element not found")
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returnVal := -1
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return returnVal
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} else if arr[mid] == searchNum {
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//fmt.Println("Element found at index:",mid)
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returnVal := mid
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return returnVal
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} else if arr[mid] > searchNum {
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endIdx = mid-1
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} else {
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startIdx = mid+1
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}
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}
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return returnVal
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}
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// Binary Search Recursive algorithm
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func BinarySearchRecursive(array *[]int,startIdx int,endIdx int, searchNum int) int {
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arr := *array
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var returnVal int
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//fmt.Println("Using the recursive Binary Search approach")
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mid := startIdx + (endIdx - startIdx)/2
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if (endIdx<startIdx) {
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//fmt.Println("Element not found")
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returnVal = -1
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return returnVal
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} else if (arr[mid] == searchNum) {
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//fmt.Println("Element found at Index:",mid)
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returnVal = mid
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return returnVal
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} else if (arr[mid] > searchNum) {
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returnVal = BinarySearchRecursive(array,startIdx,mid-1,searchNum)
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} else {
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returnVal = BinarySearchRecursive(array,mid+1,endIdx,searchNum)
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}
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return returnVal
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}
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// Unit Test for Binary Search
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func main(){
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var length,searchNum int
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fmt.Println("Enter the size of the array")
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fmt.Scanf("%d",&length)
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fmt.Println("Enter the ascending order of array elements seperated by a space")
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arr := make([]int,length)
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for i:=0;i<length;i++ {
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fmt.Scanln(&arr[i])
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}
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fmt.Println("Enter the number to search in the array")
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fmt.Scanf("%d",&searchNum)
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fmt.Println("Array:",arr)
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BinarySearchIterative(&arr,0,length-1,searchNum)
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fmt.Println("Using the recursive Binary Search approach")
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BinarySearchRecursive(&arr,0,length-1,searchNum)
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}

‎arrays/maxInSlidingWindow.go

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/*
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Given a large array of integers and a window size to searh in, find the current max value in the window
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when sliding through the window and print it
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*/
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package main
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import ("fmt"
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"container/list"
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)
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/*
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Function takes in the value of the array to search for and the window size and returns
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the maximum values
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*/
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func maxInSlidingWindow(arr *[]int,windowSize int) {
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/*
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Initializing a doublylinkedlist to store the index of the elements. We need
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a DS that can perform like a deque. Doubly Linkedlist perfectly accomplishes that
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*/
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dll := list.New()
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array := *arr
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//fmt.Println(dll.Front())
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//Traversing the array and adding the right elements to the dll
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// The first index in the dll is always the max in the current sliding window
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for idx,val := range array {
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// This ensures that if we just started the array we fill the window first element with the first element of the array
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if dll.Front() != nil {
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e := dll.Back()
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for {
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if e != nil && val >= array[e.Value.(int)]{
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dll.Remove(e)
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e = dll.Back()
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} else {
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dll.PushBack(idx)
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break
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}
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}
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//Pop the first element in the window if it doesnt fall in the window any more
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e = dll.Front()
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if e.Value.(int) < (idx - windowSize + 1) {
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e = dll.Front()
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dll.Remove(e)
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}
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} else {
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e := dll.PushBack(idx)
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if e == nil {
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fmt.Println(e)
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}
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}
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// This condition ensure that we start printing only after we have visited all the elements in the First window
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if idx >= (windowSize-1) {
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e := dll.Front()
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fmt.Println("Current Sliding Window Max: ",array[e.Value.(int)])
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}
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}
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}
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func main() {
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arr := []int{-4,2,-5,1,-1,6}
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maxInSlidingWindow(&arr,3)
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//fmt.Println(dll)
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//fmt.Println(l.Front())
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//fmt.Println(l.Back())
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}

‎arrays/searchRotatedArray.go

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/*
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Given number in a sorted array that has been rotated by some number of times. Return -1 if the number does not exist or the index if it does exist
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No duplicate entries in the array. The current solution is only for unique entries
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*/
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package main
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import ("fmt"
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bS "AlgorithmsGolang/arrays/binarySearch"
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)
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func searchRotatedArrayRecursive(array *[]int, startIdx int,endIdx int, searchNum int) int {
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arr := *array
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var returnVal int
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mid := startIdx + (endIdx - startIdx)/2
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//Case 1 and Case 2 are cases of regular binarySearch
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if arr[mid] < searchNum && arr[endIdx] >= searchNum {
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returnVal = bS.BinarySearchIterative(array,mid+1,endIdx,searchNum)
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return returnVal
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} else if arr[mid] > searchNum && arr[startIdx] <= searchNum {
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returnVal = bS.BinarySearchIterative(array,startIdx,mid-1,searchNum)
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return returnVal
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} else if arr[mid] == searchNum {
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returnVal = mid
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return returnVal
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} else if arr[mid] < searchNum && arr[mid] < arr[startIdx] {
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returnVal = searchRotatedArrayRecursive(array,startIdx,mid-1,searchNum)
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return returnVal
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} else {
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returnVal = searchRotatedArrayRecursive(array,mid+1,endIdx,searchNum)
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return returnVal
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}
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return returnVal
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}
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// Unit Test
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func main() {
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arr := []int{176,188,199,200,210,222,1,10,20,47,59,63,75,88,99,107,120,133,155,162}
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searchNum1 := 200
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searchNum2 := 176
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index1 := searchRotatedArrayRecursive(&arr,0,len(arr)-1,searchNum1)
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index2 := searchRotatedArrayRecursive(&arr,0,len(arr)-1,searchNum2)
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fmt.Println("searchNum1:",searchNum1,"is at Index:",index1)
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fmt.Println("searchNum2:",searchNum2,"is at Index:",index2)
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}

‎arrays/smallestCommonNumber.go

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/*
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Given 3 sorted arrays, find the smallest number among the three that is common to all
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else return -1
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*/
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package main()
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import ("fmt"
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"AlgorithmsGolang/arrays/binarySearch"
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)
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func smallestCommonNumber() {
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}
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func main() {
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}

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