给予一个整数数列，找出第N大的那个数。
样例输入：45 67 33 21（换行）2
样例输出：45

JavaScript(Node)实现

const readline = require('readline');
const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout
});
let flag = true;
let str, idx;
rl.on('line', function(line) {
    if (flag) {
        str = line;
        flag = false;
    } else {
        idx = line;
        console.log(findBigNum(str, idx));
        flag = true;
    }
});

function findBigNum(str, idx) {
    let arr = str.split(' ').map(val => +val);
    arr.sort((a, b) => b - a);
    return arr[idx - 1];
}

PHP实现

<?php
    $handle = fopen("php://stdin", "r");
    $line = fgets($handle);
    $flag = true;
    while ($line !== "") {
        if ($flag) {
            $str = $line;
            $flag = false;
        } else {
            $idx = $line;
            echo findBigNum($str, $idx) . "\n";
        }
        $line = fgets($handle);
    }
    fclose($handle);

    function findBigNum($str, $idx) {
        $arr = array_map("intval", explode(" ", $str));
        rsort($arr);
        return $arr[$idx - 1];
    }

C++实现

#include <iostream>
#include <string>
#include <sstream>
#include <vector>
#include <algorithm>
using namespace std;

int findBigNum(string str, string idx) {
    stringstream iss(str);
    int number;
    vector<int> vec;
    while(iss >> number) {
        vec.push_back(number);
    }
    sort(vec.begin(), vec.end(),
        [](const int a, const int b) {
            return b < a;
        }
    );
    return vec[atoi(idx.c_str()) - 1];
}

int main() {
    string line;
    bool flag = true;
    string str, idx;
    while (getline(cin, line)) {
        if (flag) {
            str = line;
            flag = false;
        } else {
            idx = line;
            cout << findBigNum(str, idx) << endl;
            flag = true;
        }
    }
    return 0;
}

以上。

个人技术博客 biebu.xin，原文链接——多语言解编程题之数列第N大