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Replace duplicates with greater than previous duplicate value
  • Difficulty Level : Medium
  • Last Updated : 03 Jan, 2020

Given an array of elements and change the array in such a way that all the elements on the array are distinct. if you are replacing a value, then the replacing value should be great than the previous value and after modification sum of the elements should be as less as possible.

Examples:

Input : arr = {1, 2, 2, 5, 8, 8, 8}
Output : 1 2 3 5 8 9 10
8 is replaced with 9 (A non-existing element greater than 8). Next duplicate occurrence of 8 is replaced with 10.

Input : arr = {1, 2, 5, 7, 8, 8, 7}
Output : 1 2 5 7 8 9 10

Input : arr = {9, 9, 9, 9, 9}
Output : 9 10 11 12 13



Source : Paytm Interview Experience 30.

This problem is a variation of this article. In the above article we had to replace the duplicates with the greatest value so far. But in this problem we have to replace elements with duplicates greater than previous duplicate value.
The idea is to find the next greater element to be replaced to minimize the total sum. To find the next greater element we have to iterate from the repeated element till the INT_MAX untill the next greater element is found.

Below is the implementation of above approach.

C++




// CPP program to replace every repeating
// element with next greater element.
#include <bits/stdc++.h>
using namespace std;
  
void replaceElements(int arr[], int n)
{
    unordered_set<int> s;
  
    for (int i = 0; i < n; i++) {
  
        // check whether the element is
        // repeated or not
        if (s.find(arr[i]) == s.end())
            s.insert(arr[i]);
  
        else {
  
            // find the next greatest element
            for (int j = arr[i] + 1; j < INT_MAX; j++) {
                if (s.find(j) == s.end()) {
                    arr[i] = j;
                    s.insert(j);
                    break;
                }
            }
        }
    }
}
  
int main()
{
    int arr[] = { 1, 2, 5, 7, 8, 8, 7 };
    int n = sizeof(arr) / sizeof(arr[0]);
  
    replaceElements(arr, n);
  
    for (int i = 0; i < n; i++)
        cout << arr[i] << " ";
    cout << "\n";
}

Java




// Java program to replace every repeating
// element with next greater element.
import java.util.HashSet;
import java.util.Set;
  
public class ReplaceDuplicateWithGreaterThanPreviousDuplicate {
  
    private static void replaceElements(int[] arr, int n)
    {
        Set<Integer> st = new HashSet<>();
        for (int i = 0; i < n; i++) {
            // check whether the element is
            // repeated or not
            if (!st.contains(arr[i])) {
                st.add(arr[i]);
            }
            else {
                // find the next greatest element
                for (int j = arr[i] + 1; j < Integer.MAX_VALUE; j++) {
                    if (!st.contains(j)) {
                        arr[i] = j;
                        st.add(j);
                        break;
                    }
                }
            }
        }
    }
    public static void main(String[] args)
    {
        int[] arr = new int[] { 1, 2, 5, 7, 8, 8, 7 };
        int n = arr.length;
        replaceElements(arr, n);
  
        for (int i = 0; i < n; i++) {
            System.out.print(arr[i] + " ");
        }
    }
}

Python3




# Python3 program to replace every repeating
# element with next greater element.
import sys
  
def replaceElements(arr, n):
  
    s = []
  
    for i in range (n):
  
        # check whether the element 
        # is repeated or not
        if arr[i] not in s:
            s.append(arr[i])
  
        else :
  
            # find the next greatest element
            for j in range(arr[i] + 1, sys.maxsize) :
                if j not in s:
                    arr[i] = j
                    s.append(j)
                    break
  
# Driver Code
if __name__ == "__main__":
  
    arr = [ 1, 2, 5, 7, 8, 8, 7 ]
    n = len(arr)
  
    replaceElements(arr, n)
  
    for i in range(n):
        print (arr[i], end = " ")
    print ()
  
# This code is contributed 
# by ChitraNayal

C#




// C# program to replace every repeating 
// element with next greater element. 
using System;
using System.Collections.Generic;
  
public class ReplaceDuplicateWithGreaterThanPreviousDuplicate 
    private static void replaceElements(int[] arr, int n) 
    
        HashSet<int> st = new HashSet<int>(); 
        for (int i = 0; i < n; i++) 
        
            // check whether the element is 
            // repeated or not 
            if (!st.Contains(arr[i])) 
            
                st.Add(arr[i]); 
            
            else
            
                // find the next greatest element 
                for (int j = arr[i] + 1; j < int.MaxValue; j++) 
                
                    if (!st.Contains(j))
                    
                        arr[i] = j; 
                        st.Add(j); 
                        break
                    
                
            
        
    
      
    // Driver Code
    public static void Main(String[] args) 
    
        int[] arr = new int[] { 1, 2, 5, 7, 8, 8, 7 }; 
        int n = arr.Length; 
        replaceElements(arr, n); 
  
        for (int i = 0; i < n; i++) 
        
            Console.Write(arr[i] + " "); 
        
    
  
// This code is contributed by PrinciRaj1992
Output:
1 2 5 7 8 9 10

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