common-child.js

'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 commonChild function below.
function commonChild(s1, s2) {
    let f = [];
    for (let i = 0; i < s1.length; i++) {
        f.push(new Array(s2.length).fill(0))
        if (s1[i] === s2[0] || s1[0] === s2[0]) f[i][0] = 1;
    }
    for (let i = 0; i < s2.length; i++) {
        if (s2[i] === s1[0] || s1[0] === s2[0]) f[0][i] = 1;
    }
    for (let i = 1; i < s1.length; i++) {
        for (let j = 1; j < s2.length; j++) {
            if (s1[i] === s2[j]) f[i][j] = f[i - 1][j - 1] + 1;
            else f[i][j] = Math.max(f[i - 1][j - 1], f[i][j - 1], f[i - 1][j]);
        }
    }
    return f[s1.length - 1][s2.length - 1];
}

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

    const s1 = readLine();

    const s2 = readLine();

    let result = commonChild(s1, s2);

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

    ws.end();
}