Added all indices of an element in array.

Author: siddhi-244

Recursion/All_indices_of_element.cpp

@@ -0,0 +1,84 @@
+// CPP program to find all indices of a number
+#include <bits/stdc++.h>
+using namespace std;
+// A recursive function to find all indices of a number in array.
+
+int allIndexes(int input[], int size,
+  int x, int output[])
+{
+
+    // If size of array is 0 then return 0
+
+    if (size == 0) {
+        return 0;
+    }
+ 
+    // recursion
+
+    int smallAns = allIndexes(input + 1,size - 1, x, output);
+ 
+
+    // If the element at first index is equal to x then add 1 to the array values and shift them right by 1 step
+
+    if (input[0] == x) {
+        for (int i = smallAns - 1; i >= 0; i--) {
+            output[i + 1] = output[i] + 1;
+        }
+        // Put the start index in front
+
+        // of the array
+
+        output[0] = 0;
+
+        smallAns++;
+
+    }
+
+    else {
+
+        // If the element at index 0 is not equal to x then add 1 to the array values and no need to shift array.
+      for (int i = smallAns - 1; i >= 0; i--) {
+
+            output[i] = output[i] + 1;
+        }
+    }
+    return smallAns;
+}
+ 
+// Function to find all indices of a number
+
+void AllIndexes(int input[], int n, int x)
+{
+
+    int output[n];
+
+    int size = allIndexes(input, n, x, output);
+
+    for (int i = 0; i < size; i++) {
+
+        cout << output[i] << " ";
+
+    }
+}
+ 
+// Driver Code
+
+int main()
+{
+    int n,arr[1000],x;
+    cin>>n;
+    for(int i=0;i<n;i++){
+      cin>>arr[i];
+    }
+    cin>>x;
+
+     
+
+    // Function call
+
+    AllIndexes(arr, n, x);
+
+     
+
+    return 0;
+}