bigger-is-greater.js

// next permutation problems, https://www.nayuki.io/page/next-lexicographical-permutation-algorithm
'use strict';

const fs = require('fs');

process.stdin.resume();
process.stdin.setEncoding('utf-8');

let inputString = '';
let currentLine = 0;

process.stdin.on('data', inputStdin => {
    inputString += inputStdin;
});

process.stdin.on('end', _ => {
    inputString = inputString.replace(/\s*$/, '')
        .split('\n')
        .map(str => str.replace(/\s*$/, ''));

    main();
});

function readLine() {
    return inputString[currentLine++];
}

// Complete the biggerIsGreater function below.
function biggerIsGreater(array) {
    array = array.split('');
    // Find non-increasing suffix
    var i = array.length - 1;
    while (i > 0 && array[i - 1] >= array[i])
        i--;
    if (i <= 0)
        return "no answer";
    
    // Find successor to pivot
    var j = array.length - 1;
    while (array[j] <= array[i - 1])
        j--;
    var temp = array[i - 1];
    array[i - 1] = array[j];
    array[j] = temp;
    
    // Reverse suffix
    j = array.length - 1;
    while (i < j) {
        temp = array[i];
        array[i] = array[j];
        array[j] = temp;
        i++;
        j--;
    }
    return array.join('');
}

function main() {
    const ws = fs.createWriteStream(process.env.OUTPUT_PATH);

    const T = parseInt(readLine(), 10);

    for (let TItr = 0; TItr < T; TItr++) {
        const w = readLine();

        let result = biggerIsGreater(w);

        ws.write(result + "\n");
    }

    ws.end();
}