Print the final string when minimum value strings get concatenated in every operation

Last Updated : 05 Mar, 2021

Given an array of strings and an array of integers where i^th integer of the array corresponds to the value of the i^th string present in the string array. Now pick two strings which have the smallest values in the integer array and sum up both the integers and concatenate the strings and add both the summed up integer to the integer array and the concatenated string to the string array, and keep repeating the whole process until only a single element is left in both the arrays. Also note that once any two strings and integers are picked they get deleted from the array and new strings and integers are added back to the respective arrays.
The task is to print the final string obtained.

Examples:

Input: str = {“Geeks”, “For”, “Geeks”}, num = {2, 3, 7}
Output: GeeksForGeeks
Pick 2 and 3 add them, and form “GeeksFor” and 5
Add them back to the arrays, str = {“GeeksFor”, “Geeks”}, num = {5, 7}
Now pick 7 and 5 add them to form “GeeksForGeeks” which is the final string.

Input: str = {“abc”, “def”, “ghi”, “jkl”}, num = {1, 4, 2, 6}
Output: jklabcghidef

Approach: The idea is to use a priority queue, and make a pair of strings and their corresponding values and store them in the priority queue and keep dequeueing two pairs from the priority queue, adding the integers and concatenating the strings and enqueuing them back into the priority queue, till the size of the queue reduces to one, and then print the only remaining string in the queue.

Below is the implementation of the above approach:

C++

// C++ implementation of the approach
#include <bits/stdc++.h>
using namespace std;
 
// Class that represents a pair
struct Priority
{
    string s;
    int count;
};
 
struct Compare 
{
    int operator()(Priority a, Priority b) 
    {
        if (a.count > b.count)
            return 1;
        else if (a.count < b.count)
            return -1;
             
        return 0;
    }
};
 
// Function that prints the final string
static void FindString(string str[], int num[],
                                     int n)
{
    priority_queue<int, vector<Priority>, Compare> p;
     
    // Add all the strings and their corresponding
    // values to the priority queue
    for(int i = 0; i < n; i++)
    {
        Priority x;
        x.s = str[i];
        x.count = num[i];
        p.push(x);
    }
     
    // Take those two strings from the priority
    // queue whose corresponding integer values
    // are smaller and add them up as well as 
    // their values and add them back to the 
    // priority queue while there are more
    // than a single element in the queue
    while (p.size() > 1) 
    {
         
        // Get the minimum valued string
        Priority x = p.top();
        p.pop();
        // p.remove(x);
         
        // Get the second minimum valued string
        Priority y = p.top();
        p.pop();
         
        // Updated integer value
        int temp = x.count + y.count;
        string sb = x.s + y.s;
         
        // Create new entry for the queue
        Priority z;
        z.count = temp;
        z.s = sb;
         
        // Add to the queue
        p.push(z);
    }
     
    // Print the only remaining string
    Priority z = p.top();
    p.pop();
     
    cout << z.s << endl;
}
 
// Driver code
int main() 
{
    string str[] = { "Geeks", "For", "Geeks" };
    int num[] = { 2, 3, 7 };
    int n = sizeof(num) / sizeof(int);
     
    FindString(str, num, n);
}
 
// This code is contributed by sanjeev2552

Java

// Java implementation of the approach
import java.util.*;
import java.lang.*;
 
// Class that represents a pair
class Priority {
    String s;
    int count;
}
 
class PQ implements Comparator<Priority> {
    public int compare(Priority a, Priority b)
    {
        if (a.count > b.count)
            return 1;
        else if (a.count < b.count)
            return -1;
        return 0;
    }
}
 
class GFG {
 
    // Function that prints the final string
    static void FindString(String str[], int num[], int n)
    {
        Comparator<Priority> comparator = new PQ();
        PriorityQueue<Priority> p
            = new PriorityQueue<Priority>(comparator);
 
        // Add all the strings and their corresponding
        // values to the priority queue
        for (int i = 0; i < n; i++) {
            Priority x = new Priority();
            x.s = str[i];
            x.count = num[i];
            p.add(x);
        }
 
        // Take those two strings from the priority
        // queue whose corresponding integer values are smaller
        // and add them up as well as their values and
        // add them back to the priority queue
        // while there are more than a single element in the queue
        while (p.size() > 1) {
 
            // Get the minium valued string
            Priority x = p.poll();
            p.remove(x);
 
            // Get the second minium valued string
            Priority y = p.poll();
            p.remove(y);
 
            // Updated integer value
            int temp = x.count + y.count;
            String sb = x.s + y.s;
 
            // Create new entry for the queue
            Priority z = new Priority();
            z.count = temp;
            z.s = sb;
 
            // Add to the queue
            p.add(z);
        }
 
        // Print the only remaining string
        Priority z = p.poll();
        System.out.println(z.s);
    }
 
    // Driver code
    public static void main(String[] args)
    {
        String str[] = { "Geeks", "For", "Geeks" };
        int num[] = { 2, 3, 7 };
        int n = num.length;
 
        FindString(str, num, n);
    }
}

Output:

GeeksForGeeks

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