题解 | 找出重复的数字

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

int main() {
    // 使用HashSet存储已出现的数字
    unordered_set<int> seen;
    
    // 读取输入并查找重复数字
    int num;
    while(cin >> num) {
        if(seen.count(num)) {
            cout << num << endl;
            return 0;
        }
        seen.insert(num);
    }
    
    return 0;
}

import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        
        // 使用HashSet存储已出现的数字
        Set<Integer> seen = new HashSet<>();
        
        // 读取输入并查找重复数字
        while(sc.hasNextInt()) {
            int num = sc.nextInt();
            if(seen.contains(num)) {
                System.out.println(num);
                return;
            }
            seen.add(num);
        }
    }
}

def find_duplicate():
    # 使用set存储已出现的数字
    seen = set()
    
    # 读取输入并查找重复数字
    nums = list(map(int, input().split()))
    
    for num in nums:
        if num in seen:
            print(num)
            return
        seen.add(num)

if __name__ == "__main__":
    find_duplicate()