Merge pull request #373 from JitinSaxenaa/binarysearch

Binary Search

Author: Pradeepsingh61

CPP/algorithms/searching/Seacrh/binary_search.cpp

@@ -1,56 +1,73 @@
-#include<iostream>
-using namespace std;
+#include <stdio.h>
 
+/*
+======================================================
+Binary Search Algorithm
+======================================================
+Description:
+Binary Search is an efficient algorithm to find the position of a target value
+in a sorted array. It repeatedly divides the search interval in half. 
 
+Key Idea:
+1. Start with the entire array as the search interval.
+2. Find the middle element.
+3. If the middle element is equal to the target, return its index.
+4. If the target is smaller, search the left half.
+5. If the target is larger, search the right half.
+6. Repeat until the target is found or interval is empty.
 
+Time Complexity: O(log n)
+Space Complexity: O(1) for iterative implementation
+======================================================
+*/
 
-int binarysearch(int arr[], int size, int key){
-    int s = 0;         //startingpoint
-    int e = size-1;         //ending point
-    while(s<size){
-        int mid = (s+(e-1))/2;
-        if(arr[mid]==key){
-            return mid;
+// Iterative Binary Search function
+int binarySearch(int arr[], int size, int target) {
+    int left = 0;
+    int right = size - 1;
+
+    while (left <= right) {
+        int mid = left + (right - left) / 2; // prevents overflow
+
+        if (arr[mid] == target) {
+            return mid; // Target found
         }
-        else if(arr[mid] > key){
-            e = mid-1;
+        else if (arr[mid] < target) {
+            left = mid + 1; // Search in right half
         }
-        else{
-            s = mid+1;
+        else {
+            right = mid - 1; // Search in left half
         }
     }
-    //if not work then we ll return -1
-    return -1;
-}
-
-
-
 
+    return -1; // Target not found
+}
 
+int main() {
+    int n, target;
 
+    // Input the size of the array
+    printf("Enter size of array: ");
+    scanf("%d", &n);
 
+    int arr[n];
+    printf("Enter %d elements in sorted order: ", n);
+    for (int i = 0; i < n; i++) {
+        scanf("%d", &arr[i]);
+    }
 
-int main (){
+    // Input the target value
+    printf("Enter the target value: ");
+    scanf("%d", &target);
 
-    int size;
-    cout<<"enter the size of the array : ";
-    cin>>size;
-    int key;
-    cout<<"enter the key : ";
-    cin>>key;
+    // Call Binary Search
+    int result = binarySearch(arr, n, target);
 
-    int arr[size];
-    cout<<"Enter the elements of array : "<<endl;
-    for(int i = 0; i<size; i++){
-        cin>>arr[i];
-    }
-    int result = binarysearch(arr,size,key);
-    if(result == -1){
-        cout<<"Element is not present in the array"<<endl;
-        }
-    else{
-        cout<<"Element is present at index "<<result<<endl;
+    if (result != -1) {
+        printf("Target %d found at index %d.\n", target, result);
+    } else {
+        printf("Target %d not found in the array.\n", target);
     }
 
     return 0;
-}
+}