Added new questions in binary search topic

DSA Topic Wise🔥/Algorithms/Searching/Questions/03. Count Occurrences in Sorted/code.cpp

@@ -13,17 +13,55 @@ Input -
 1 10 10 10 20 20 40
 
 Output -
-5
+2
 */
 
 // Time Complexity : O(log n) 
 // Auxiliary Space : O(1) 
-int solution(int *arr, int start, int end, int x){
+
+int lastOccurrence(int *arr, int start, int end, int x){
   int ans = -1;
+  while (start <= end){
+    int mid = (start + end)/2;
 
+    if(arr[mid] > x)
+      end = mid - 1;
+    else if(arr[mid] < x)
+      start = mid + 1;
+    else{
+      ans = mid;
+      start = mid + 1;
+    }
+  }
   return ans;
 }
 
+int firstOccurrence(int *arr, int start, int end, int x){
+  int ans = -1;
+  while (start <= end){
+    int mid = (start + end)/2;
+
+    if(arr[mid] > x)
+      end = mid-1;
+    else if(arr[mid] < x) 
+      start = mid+1;
+    else{
+      ans = mid;
+      end = mid - 1;
+    } 
+  }
+  return ans;
+}
+
+int solution(int *arr, int start, int end, int x){
+  int first = firstOccurrence(arr, start, end, x);
+
+  if(first == -1)
+    return 0;
+  else 
+    return (lastOccurrence(arr, start, end, x) - first + 1);
+}
+
 int main(){
   ios_base::sync_with_stdio(false);
   cin.tie(NULL);

DSA Topic Wise🔥/Algorithms/Searching/Questions/04. Count 1s in a Sorted Binary Array/code.cpp

@@ -0,0 +1,79 @@
+#include <bits/stdc++.h>
+using namespace std;
+#define ll long long
+#define db double
+#define ld long double
+#define el "\n"
+
+/*
+Input -
+1
+7
+0 0 0 1 1 1 1 
+
+Output -
+4
+*/
+
+int lastOccurrence(int *arr, int start, int end, int x){
+  int ans = -1;
+  while (start <= end){
+    int mid = (start + end)/2;
+
+    if(arr[mid] < x)
+      start = mid + 1;
+    else{
+      ans = mid;
+      start = mid + 1;
+    }
+  }
+  return ans;
+}
+
+int firstOccurrence(int *arr, int start, int end, int x){
+  int ans = -1;
+  while (start <= end){
+    int mid = (start + end)/2;
+
+    if(arr[mid] < x) 
+      start = mid+1;
+    else{
+      ans = mid;
+      end = mid - 1;
+    } 
+  }
+  return ans;
+}
+
+// Time Complexity : O(log n) 
+// Auxiliary Space : O(1) 
+int solution(int *arr, int start, int end){
+  int x = 1;
+
+  int first = firstOccurrence(arr, start, end, x);
+
+  if(first == -1)
+    return 0;
+  else 
+    return (lastOccurrence(arr, start, end, x) - first + 1);
+}
+
+int main(){
+  ios_base::sync_with_stdio(false);
+  cin.tie(NULL);
+
+  int t;
+  cin >> t;
+  while (t--){
+    int n;
+    cin >> n;
+
+    int arr[n];
+    for (int i = 0; i < n; i++)
+      cin >> arr[i];
+
+    cout << "Solution -> " << solution(arr, 0, n - 1) << el;
+  }
+
+  return 0;
+}