HackerRank Candies problem solution

In this HackerRank Candies problem solution, Alice is a kindergarten teacher. She wants to give some candies to the children in her class.  All the children sit in a line and each of them has a rating score according to his or her performance in the class.  Alice wants to give at least 1 candy to each child. If two children sit next to each other, then the one with the higher rating must get more candies. Alice wants to minimize the total number of candies she must buy.

Function Description

Complete the candies function in the editor below.

candies has the following parameter(s):

• int n: the number of children in the class
• int arr[n]: the ratings of each student

Returns

• int: the minimum number of candies Alice must buy

HackerRank Candies problem solution in Python.

N = int(input())
a = []
while N>0:
	a.append(int(input()))
	N -= 1
N = len(a)
left, right, num = [[0 for i in range(N)] for j in range(3)]
p = 1
while p<N:
	if a[p] > a[p-1]:
		left[p] = left[p-1] + 1
	p += 1
p = N-2
while p>=0:
	if a[p] > a[p+1]:
		right[p] = right[p+1] + 1
	p -= 1
p = 0
while p<N:
	num[p] = 1 + max(left[p], right[p])
	p += 1

print(sum(num))

Candies problem solution in Java.

import java.io.*;
import java.math.*;
import java.security.*;
import java.text.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.regex.*;

public class Solution {

    // Complete the candies function below.
    static long candies(int n, int[] arr) {

  int[] candies = new int[n];
  candies[0] = 1;
  for (int i = 1; i < n; i++) {
    if (arr[i] > arr[i - 1]) {
      candies[i] = candies[i - 1] + 1;
    } else {
      candies[i] = 1;
    }
  }

  for (int i = n - 2; i >= 0; i--) {
    if (arr[i] > arr[i + 1] && candies[i] <= candies[i + 1]) {
      candies[i] = candies[i + 1] + 1;
    }
  }

  long sum = 0;
  for (int c : candies) {
    sum += c;
  }
  return sum;
}

    private static final Scanner scanner = new Scanner(System.in);

    public static void main(String[] args) throws IOException {
        BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(System.getenv("OUTPUT_PATH")));

        int n = scanner.nextInt();
        scanner.skip("(rn|[nru2028u2029u0085])?");

        int[] arr = new int[n];

        for (int i = 0; i < n; i++) {
            int arrItem = scanner.nextInt();
            scanner.skip("(rn|[nru2028u2029u0085])?");
            arr[i] = arrItem;
        }

        long result = candies(n, arr);

        bufferedWriter.write(String.valueOf(result));
        bufferedWriter.newLine();

        bufferedWriter.close();

        scanner.close();
    }
}

Problem solution in C++ programming.

#include <iostream>
#include <vector>
using namespace std;
int nums[100001]; // ratings
int allocated[100001]; // candies given. defaults to 0 (not processed)
vector<int> pos_by_rating[100001];
int main()
{
	int N;
	cin >> N;
	
	for (int x = 0; x < N; x++)
	{
		cin >> nums[x];
		allocated[x] = 0;
		pos_by_rating[nums[x]].push_back(x);
	}

	for (int rating = 1; rating <= 100000; rating++)
	{
		for (int q = 0; q < pos_by_rating[rating].size(); q++)
		{
			int pos = pos_by_rating[rating][q];
			int m = 0;
			if (pos > 0 && nums[pos-1] < nums[pos])
			{
				m = max(m, allocated[pos-1]);
			}

			if (pos < N-1 && nums[pos+1] < nums[pos])
			{
				m = max(m, allocated[pos+1]);
			}

			allocated[pos] = m+1;
		}
	}
		
	int sum = 0;
	for (int x = 0; x < N; x++)
	{
		//cout << allocated[x] << endl;
		sum += allocated[x];
	}
	cout << sum << endl;

	return 0;
}

Problem solution in C programming.

#include <stdio.h>
#include <stdlib.h>

#define MAXN 100000

struct stu{
    int id;
    int rating;
};

int comp( const void*p1, const void*p2){
    return ((struct stu*)p1)->rating - ((struct stu*)p2)->rating;
}

struct stu student[MAXN];
int candies[MAXN];
int ratings[MAXN];

int main(int argc, char *argv[])
{
    int N;
    int i,j;
    int candy;
    int id;
    long long sumcandies = 0;

    scanf("%d",&N);
    for(i = 0; i < N; i++){
        scanf("%d",&student[i].rating);
        student[i].id = i;
        ratings[i] = student[i].rating;
    }

    qsort(student,N,sizeof(struct stu),comp);
    
    for(i = 0; i < N; i++){
        id = student[i].id;
        candy = 1;

        if(id > 0){
            if(candies[id-1] != 0 && ratings[id] > ratings[id-1]){
                candy = candies[id-1] + 1;
            }
        }

        if(id < N-1){
            if(candies[id+1] != 0 && ratings[id] > ratings[id+1] &&
               candy <= candies[id+1]){
                candy = candies[id+1] + 1;
            }
        }

        sumcandies += candy;
        candies[id] = candy;
    }

    printf("%lldn",sumcandies);
    return 0;
}

Problem solution in JavaScript programming.

function processData(input) {
    //Enter your code here
    var arr = input.split('n');
    var sum = 1, tempRank = 1, peakPos = 1, peakVal = 1;
    for (var i = 2; i < arr.length; i++) {
        if (parseInt(arr[i]) > parseInt(arr[i-1])) {
            tempRank++;
            sum += tempRank;
            peakPos = i;
            peakVal = tempRank;
 //          console.log("bigger: " + sum);
        } else if (parseInt(arr[i]) < parseInt(arr[i-1])) {
            if (tempRank > 1) {
                peakVal--;
                sum++;
            } else {
                sum += (i - peakPos);
                peakVal--;
                if (peakVal == 0) {
                    peakVal = 1;
                    sum++;
                }
            }
            tempRank = 1;
//           console.log("smaller: " + sum);
        } else {
           /* if (tempRank > 1) {
                peakVal--;
                if (peakVal == 0) {
                    peakVal = 1;
                    sum++;
                }
            }*/
            
            peakVal = 1;
            peakPos = i;
            tempRank = 1;
            sum++;
 //             console.log("equal: " + sum);
        }
    }
    
    console.log(sum);
} 

process.stdin.resume();
process.stdin.setEncoding("ascii");
_input = "";
process.stdin.on("data", function (input) {
    _input += input;
});

process.stdin.on("end", function () {
   processData(_input);
});