Merge pull request ZoranPandovski#3310 from shivesh41kr/patch-3

Equilibrium Point in an Array

search/Equilibrium_Point_in_an_Array.cpp

@@ -0,0 +1,44 @@
+//Equilibrium index of an Array using Array-Sum
+
+#include <bits/stdc++.h>
+using namespace std;
+
+int equilibrium(int arr[], int n)
+{
+    int sum = 0; // initialize sum of whole array
+    int leftsum = 0; // initialize leftsum
+
+    /* Find sum of the whole array */
+    for (int i = 0; i < n; ++i)
+        sum += arr[i];
+
+    for (int i = 0; i < n; ++i) {
+        sum -= arr[i]; // sum is now right sum for index i
+
+        if (leftsum == sum)
+            return i;
+
+        leftsum += arr[i];
+    }
+
+    /* If no equilibrium index found, then return 0 */
+    return -1;
+}
+
+int main()
+{
+    int arr[] = { -7, 1, 5, 2, -4, 3, 0 };
+    int arr_size = sizeof(arr) / sizeof(arr[0]);
+
+    // Function call
+    cout << "First equilibrium index is "
+         << equilibrium(arr, arr_size);
+    return 0;
+}
+
+/*
+
+ Time Complexity: O(N)
+Auxiliary Space: O(1)
+
+*/