How to Take Input in Competitive Programming

This guide shows how to read input using C++, C, Python and Java. We’ll use the following example problem:

Read an integer n, then read in n names. For each name, print Hello <name>!

C++

#include <iostream>
#include <string>
using namespace std;

int main() {
    int x;
    cin >> x;
    for (int i = 0; i < x; ++i) {
        string name;
        cin >> name;
        cout << "Hello " << name << "!" << '\n';
    }
    return 0;
}

C

#include <stdio.h>

int main() {
    int x;
    scanf("%d", &x);
    for (int i = 0; i < x; ++i) {
        char name[100]; // Ensure name array is large enough
        scanf("%s", name);
        printf("Hello %s!\n", name);
    }
    return 0;
}

Python (3.x)

a = int(input())
for i in range(a):
    z = input()
    print("Hello " + z + "!") # can also do print(f"Hello {z}!")

Additionally, if there are several space-separated integers in the input (e.g. 1 2 3 4), then you can extract it as follows:

nums = list(map(int, input().split()))
# Print the contents of nums:
for n in nums:
    print(n)

Java

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();
        for (int i = 0; i < a; i++) {
            String name = sc.next();
            System.out.println("Hello " + name + "!");
        }
    }
}

Sample Input

3
Adelaide
Toronto
Singapore

Sample Output

Hello Adelaide!
Hello Toronto!
Hello Singapore!

You may output at any point of the program. Your full output will be compared against the expected output.