Competitive Programming Practice.

costReducer.java

// Adding numbers with reduced cost.
/*
    Victor has an array of size n. He loves to play with these n numbers.
    Each time he plays with them, he picks up two consicutive numbers and
    adds them. On adding both the numbers, it costs him k*(sum of numbers).
    
    Find the minimum cost of adding all the numbers.
*/

import java.util.*;
import javafx.util.Pair;

public class Main {
	public static void main(String[] args) {
		Integer inputArray[] = new Integer[] {4,5,6,7}; // from user input array of size n
		Integer costMultiplier = 3; // from user input cost multiplier i.e. k
		ArrayList<Integer> array = new ArrayList<Integer>(Arrays.asList(inputArray));
		ArrayList<Integer> reducedCosts = new ArrayList<Integer>();
		Integer totalCost = 0;

		while(array.size() > 1) {
		    Pair<Integer, ArrayList> reduced = costReducer(array);
		    reducedCosts.add(reduced.getKey());
		    array = reduced.getValue();
		}
		
		for (int i=0; i<reducedCosts.size(); i++ ){
		    totalCost += reducedCosts.get(i)*costMultiplier;   
		}
		System.out.println(totalCost);
	}
	
	public static Pair<Integer, ArrayList> costReducer(ArrayList<Integer> inputArray) {
	    int minIdx = findMinIdx(inputArray);
	    Integer cost = 0;
		int toRemoveIdx = 0;
        if(minIdx == 0) {
            cost = inputArray.get(minIdx) + inputArray.get(minIdx+1);
            toRemoveIdx = minIdx+1;
        } else if(minIdx == inputArray.size()-1){
            cost = inputArray.get(minIdx) + inputArray.get(minIdx-1);
            toRemoveIdx = minIdx-1;
        } else {
            if(inputArray.get(minIdx-1) < inputArray.get(minIdx+1)){
                cost = inputArray.get(minIdx)+inputArray.get(minIdx-1);
                toRemoveIdx = minIdx-1;
            } else {
                cost = inputArray.get(minIdx)+inputArray.get(minIdx+1);
                toRemoveIdx = minIdx+1;
            }
        }
        if(minIdx < toRemoveIdx) {
            inputArray.set(minIdx, cost);
            inputArray.remove(toRemoveIdx);
        } else {
            inputArray.set(toRemoveIdx, cost);
            inputArray.remove(minIdx);
        }
        return new Pair<Integer, ArrayList>(cost, inputArray);
	}
	
	public static Integer findMinIdx(ArrayList<Integer> list) { 
        Integer min = Integer.MAX_VALUE; 
        Integer minIdx = list.size() - 1;
        for (Integer i = 0; i < list.size(); i++ ) {
            if (min > list.get(i)) {
                min = list.get(i);
                minIdx = i;
            }
        }
        return minIdx;
    }
}

4 errors occured. 1.pair not found

Can you share the testcase?

javac /tmp/qkGsnAOZQD/Main.java
/tmp/qkGsnAOZQD/Main.java:5: error: package javafx.util does not exist
import javafx.util.Pair;
^
/tmp/qkGsnAOZQD/Main.java:27: error: cannot find symbol
public static Pair<Integer, ArrayList> costReducer(ArrayList inputArray) {
^
symbol: class Pair
location: class Main
/tmp/qkGsnAOZQD/Main.java:16: error: cannot find symbol
Pair<Integer, ArrayList> reduced = costReducer(array);
^
symbol: class Pair
location: class Main
/tmp/qkGsnAOZQD/Main.java:53: error: cannot find symbol
return new Pair<Integer, ArrayList>(cost, inputArray);
^
symbol: class Pair
location: class Main
4 errors