counting-valleys.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 countingValleys function below.
function countingValleys(n, s) {
    var count = 0;
    var level = 0;
    for (var c = 0; c < n; c++) {
        if (s[c] === "U")
            level ++;
        if(s[c] === "D")
            level --;
        if(level === 0 && s[c] === "U")
            count++;

    }
    return count;
}

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

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

    const s = readLine();

    let result = countingValleys(n, s);

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

    ws.end();
}