add 41.42.43.44.45. golang

Author: zj972

README.md

@@ -44,6 +44,11 @@
 |038|Count and Say|[JavaScript & Golang](https://github.com/zj972/leetcode/tree/master/code/038.%20Count%20and%20Say)|Easy|
 |039|Combination Sum|[Golang](https://github.com/zj972/leetcode/tree/master/code/039.%20Combination%20Sum)|Medium|
 |040|Combination Sum II|[Golang](https://github.com/zj972/leetcode/tree/master/code/040.%20Combination%20Sum%20II)|Medium|
+|041|First Missing Positive|[Golang](https://github.com/zj972/leetcode/tree/master/code/041.%20First%20Missing%20Positive)|Hard|
+|042|Trapping Rain Water|[Golang](https://github.com/zj972/leetcode/tree/master/code/042.%20Trapping%20Rain%20Water)|Hard|
+|043|Multiply Strings|[Golang](https://github.com/zj972/leetcode/tree/master/code/043.%20Multiply%20Strings)|Medium|
+|044|Wildcard Matching|[Golang](https://github.com/zj972/leetcode/tree/master/code/044.%20Wildcard%20Matching)|Hard|
+|045|Jump Game II|[Golang](https://github.com/zj972/leetcode/tree/master/code/045.%20Jump%20Game%20II)|Hard|
 |058|Length of Last Word|[JavaScript](https://github.com/zj972/leetcode/tree/master/code/058.%20Length%20of%20Last%20Word)|Easy|
 |062|Unique Paths|[JavaScript](https://github.com/zj972/leetcode/tree/master/code/062.%20Unique%20Paths)|Medium|
 |066|Plus One|[JavaScript](https://github.com/zj972/leetcode/tree/master/code/066.%20Plus%20One)|Easy|

code/002. Add Two Numbers/main.go

@@ -62,7 +62,7 @@ func main() {
 	}
 }
 
-// wrong answer by 刘乾
+// wrong answer by Leo
 //func addTwoNumbers(l1 *ListNode, l2 *ListNode) *ListNode {
 //	out := new(ListNode)
 //	out.Val = 0

code/017. Letter Combinations of a Phone Number/README.md

@@ -9,7 +9,9 @@ A mapping of digit to letters (just like on the telephone buttons) is given belo
 ##### Example:
 
 Input: "23"
+
 Output: ["ad", "ae", "af", "bd", "be", "bf", "cd", "ce", "cf"].
-Note:
+
+##### Note:
 
 Although the above answer is in lexicographical order, your answer could be in any order you want.

code/041. First Missing Positive/README.md

@@ -0,0 +1,49 @@
+# 41. First Missing Positive
+
+Given an unsorted integer array, find the smallest missing positive integer.
+
+##### Example 1:
+
+Input: [1,2,0]
+
+Output: 3
+
+##### Example 2:
+
+Input: [3,4,-1,1]
+
+Output: 2
+
+##### Example 3:
+
+Input: [7,8,9,11,12]
+
+Output: 1
+
+##### Note:
+
+Your algorithm should run in O(n) time and uses constant extra space.
+
+给定一个未排序的整数数组，找出其中没有出现的最小的正整数。
+
+##### 示例 1:
+
+输入: [1,2,0]
+
+输出: 3
+
+##### 示例 2:
+
+输入: [3,4,-1,1]
+
+输出: 2
+
+##### 示例 3:
+
+输入: [7,8,9,11,12]
+
+输出: 1
+
+##### 说明:
+
+你的算法的时间复杂度应为O(n)，并且只能使用常数级别的空间。

code/041. First Missing Positive/main.go

@@ -0,0 +1,47 @@
+package main
+
+import (
+	"fmt"
+	"sort"
+)
+
+//use sort
+//Runtime: 0 ms, faster than 100.00% of Go online submissions for First Missing Positive.
+//func firstMissingPositive(nums []int) int {
+//	sort.Ints(nums)
+//	var j = 0
+//	for i := 0; i < len(nums); i++ {
+//		if nums[i] < 1 {
+//			continue
+//		}
+//		if j != nums[i] {
+//			if j+1 == nums[i] {
+//				j++
+//				continue
+//			}
+//			return j + 1
+//		}
+//	}
+//	return j + 1
+//}
+
+//no use sort
+//Runtime: 0 ms, faster than 100.00% of Go online submissions for First Missing Positive.
+func firstMissingPositive(nums []int) int {
+	for i := 0; i < len(nums); i++ {
+		for nums[i] != i+1 && nums[i] > 0 && nums[i] <= len(nums) && nums[nums[i]-1] != nums[i] {
+			nums[i], nums[nums[i]-1] = nums[nums[i]-1], nums[i]
+		}
+	}
+	for i := 0; i < len(nums); i++ {
+		if nums[i] != i+1 {
+			return i + 1
+		}
+	}
+	return len(nums) + 1
+}
+
+func main() {
+	var data = []int{1, 2, 2, 3, 6, 7}
+	fmt.Println(firstMissingPositive(data))
+}

code/042. Trapping Rain Water/README.md

@@ -0,0 +1,25 @@
+# 42. Trapping Rain Water
+
+Given n non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it is able to trap after raining.
+
+![img](http://www.leetcode.com/static/images/problemset/rainwatertrap.png)
+
+The above elevation map is represented by array [0,1,0,2,1,0,1,3,2,1,2,1]. In this case, 6 units of rain water (blue section) are being trapped. Thanks Marcos for contributing this image!
+
+##### Example:
+
+Input: [0,1,0,2,1,0,1,3,2,1,2,1]
+
+Output: 6
+
+给定 n 个非负整数表示每个宽度为 1 的柱子的高度图，计算按此排列的柱子，下雨之后能接多少雨水。
+
+![img](http://www.leetcode.com/static/images/problemset/rainwatertrap.png)
+
+上面是由数组 [0,1,0,2,1,0,1,3,2,1,2,1] 表示的高度图，在这种情况下，可以接 6 个单位的雨水（蓝色部分表示雨水）。 感谢 Marcos 贡献此图。
+
+##### 示例:
+
+输入: [0,1,0,2,1,0,1,3,2,1,2,1]
+
+输出: 6

code/042. Trapping Rain Water/main.go

@@ -0,0 +1,82 @@
+package main
+
+import (
+	"fmt"
+)
+
+//Runtime: 4 ms, faster than 100.00% of Go online submissions for Trapping Rain Water.
+//func trap(height []int) int {
+//	var sum int
+//	var i int
+//	for i < len(height) {
+//		if height[i] == 0 {
+//			i++
+//			continue
+//		}
+//		h := height[i]
+//		var j int = i + 1
+//		var right int
+//		var tmp int
+//		var maxJ int = i + 1
+//		for j < len(height) {
+//			if height[j] < h {
+//				if height[maxJ] < height[j] {
+//					maxJ = j
+//				}
+//				tmp += height[j]
+//				j++
+//				continue
+//			}
+//			right = height[j]
+//			break
+//		}
+//		if right == 0 {
+//			if maxJ == i+1 {
+//				i++
+//				continue
+//			}
+//			j = maxJ
+//			h = height[j]
+//			tmp = 0
+//			for k := i + 1; k < j; k++ {
+//				tmp += height[k]
+//			}
+//		}
+//		sum += (j-i-1)*h - tmp
+//		i = j
+//	}
+//	return sum
+//}
+
+//Runtime: 4 ms, faster than 100.00% of Go online submissions for Trapping Rain Water.
+func trap(height []int) int {
+	leng := len(height)
+	left := 0
+	right := leng - 1
+	sum := 0
+	maxRight := 0
+	maxLeft := 0
+	for left <= right {
+		if height[left] <= height[right] {
+			if height[left] >= maxLeft {
+				maxLeft = height[left]
+			} else {
+				sum += maxLeft - height[left]
+			}
+			left++
+		} else {
+			if height[right] >= maxRight {
+				maxRight = height[right]
+			} else {
+				sum += maxRight - height[right]
+			}
+			right--
+		}
+	}
+	return sum
+}
+
+func main() {
+	var data = []int{4, 2, 3}
+	fmt.Println(trap(data))
+}

code/043. Multiply Strings/README.md

@@ -0,0 +1,49 @@
+# 43. Multiply Strings
+
+Given two non-negative integers num1 and num2 represented as strings, return the product of num1 and num2, also represented as a string.
+
+##### Example 1:
+
+Input: num1 = "2", num2 = "3"
+
+Output: "6"
+
+##### Example 2:
+
+Input: num1 = "123", num2 = "456"
+
+Output: "56088"
+
+##### Note:
+
+1.The length of both num1 and num2 is < 110.
+
+2.Both num1 and num2 contain only digits 0-9.
+
+3.Both num1 and num2 do not contain any leading zero, except the number 0 itself.
+
+4.You must not use any built-in BigInteger library or convert the inputs to integer directly.
+
+给定两个以字符串形式表示的非负整数 num1 和 num2，返回 num1 和 num2 的乘积，它们的乘积也表示为字符串形式。
+
+##### 示例 1:
+
+输入: num1 = "2", num2 = "3"
+
+输出: "6"
+
+##### 示例 2:
+
+输入: num1 = "123", num2 = "456"
+
+输出: "56088"
+
+##### 说明：
+
+1.num1 和 num2 的长度小于110。
+
+2.num1 和 num2 只包含数字 0-9。
+
+3.num1 和 num2 均不以零开头，除非是数字 0 本身。
+
+4.不能使用任何标准库的大数类型（比如 BigInteger）或直接将输入转换为整数来处理。

code/043. Multiply Strings/main.go

@@ -0,0 +1,40 @@
+package main
+
+import (
+	"fmt"
+)
+
+//Runtime: 0 ms, faster than 100.00% of Go online submissions for Multiply Strings.
+func multiply(num1 string, num2 string) string {
+	if num1 == "0" || num2 == "0" {
+		return "0"
+	}
+
+	list := make([]uint8, len(num1)+len(num2))
+	for l := 0; l < len(list); l++ {
+		list[l] = 48
+	}
+	for i := len(num1) - 1; i >= 0; i-- {
+		var up uint8
+		for j := len(num2) - 1; j >= 0; j-- {
+			tmp := (num1[i]-48)*(num2[j]-48) + (list[i+j+1] - 48) + up
+			up = tmp / 10
+			list[i+j+1] = tmp%10 + 48
+		}
+		head := i
+		for up != 0 {
+			tmp := list[head] - 48 + up
+			up = tmp / 10
+			list[head] = tmp%10 + 48
+			head--
+		}
+	}
+	if list[0] == 48 {
+		list = list[1:]
+	}
+	return string(list)
+}
+
+func main() {
+	fmt.Println(multiply("123", "456"))
+}