Find index of an extra element present in one sorted array | C ++ program to find an extra element present in arr1 [ ] ; Returns index of extra element in arr1 [ ] . n is size of arr2 [ ] . Size of arr1 [ ] is n - 1. ; Initialize result ; left and right are end points denoting the current range . ; If middle element is same of both arrays , it means that extra element is after mid so we update left to mid + 1 ; If middle element is different of the arrays , it means that the index we are searching for is either mid , or before mid . Hence we update right to mid - 1. ; when right is greater than left our search is complete . ; Driver code ; Solve is passed both arrays
#include <iostream> NEW_LINE using namespace std ; int findExtra ( int arr1 [ ] , int arr2 [ ] , int n ) { int index = n ; int left = 0 , right = n - 1 ; while ( left <= right ) { int mid = ( left + right ) / 2 ; if ( arr2 [ mid ] == arr1 [ mid ] ) left = mid + 1 ; else { index = mid ; right = mid - 1 ; } } return index ; } int main ( ) { int arr1 [ ] = { 2 , 4 , 6 , 8 , 10 , 12 , 13 } ; int arr2 [ ] = { 2 , 4 , 6 , 8 , 10 , 12 } ; int n = sizeof ( arr2 ) / sizeof ( arr2 [ 0 ] ) ; cout << findExtra ( arr1 , arr2 , n ) ; return 0 ; }