Find Minimum Distance Between Two Numbers in C++

Suppose we have one unsorted array A, and two numbers x and y. We have to find the minimum distance between x and y in A. The array can also contain duplicate elements. So if the array is A = [2, 5, 3, 5, 4, 4, 2, 3], x = 3 and y = 2, then the minimum distance between 3 and 2 is just 1.

To solve this, we have to follow these steps,

• Traverse the array from left to right and stop if either x or y has found. Then store the index of that position into prev
• Now traverse the array after the index prev, if the element with current index i matches with either x or y, then check if it is different from A[prev], if that is different, then update the min index if needed, if that are different, then update prev as prev := i

Example

#include<iostream>
using namespace std;
int findMinDistance(int A[], int n, int x, int y) {
   int i = 0;
   int distance = INT_MAX;
   int prev_index;
   for (i = 0; i < n; i++) {
      if (A[i] == x || A[i] == y) {
         prev_index = i;
         break;
      }
   }
   while (i < n) {
      if (A[i] == x || A[i] == y) {
         if ( A[prev_index] != A[i] && (i - prev_index) < distance ){
            distance = i - prev_index;
            prev_index = i;
         } else
            prev_index = i;
      }
      i++;
   }
   return distance;
}
int main() {
   int arr[] = {2, 5, 3, 5, 4, 4, 2, 3};
   int n = sizeof(arr) / sizeof(arr[0]);
   int x = 3;
   int y = 2;
   cout << "Minimum distance between " << x << " and " << y << " is: "<< findMinDistance(arr, n, x, y);
}

Output

Minimum distance between 3 and 2 is: 1