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', function(inputStdin) {
    inputString += inputStdin;
});

process.stdin.on('end', function() {
    inputString = inputString.split('\n');

    main();
});

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

/*
 * Complete the 'countingValleys' function below.
 *
 * The function is expected to return an INTEGER.
 * The function accepts following parameters:
 *  1. INTEGER steps
 *  2. STRING path
 */

function countingValleys(steps, path) {
    // Write your code here
    var seaLevel=0,valleys=0,mountains = 0;
    for(let step=0;step<steps;step++){
        
        if(path[step] == 'U')
                  seaLevel++;
        else if(path[step]=='D')
                  seaLevel--;
        if(seaLevel == 0 ){
            if( path[step] == 'U' ) //Hiker finished 1 valley
                      valleys++;
            else if( path[step] == 'D')
                      mountains++; //Hiker finsihed 1 mountain
        }
               
    }
    return valleys;
}

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

    const steps = parseInt(readLine().trim(), 10);

    const path = readLine();

    const result = countingValleys(steps, path);

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

    ws.end();
}