0649-dota2-senate.js

/**
 * 649. Dota2 Senate
 * https://leetcode.com/problems/dota2-senate/
 * Difficulty: Medium
 *
 * In the world of Dota2, there are two parties: the Radiant and the Dire.
 *
 * The Dota2 senate consists of senators coming from two parties. Now the Senate wants
 * to decide on a change in the Dota2 game. The voting for this change is a round-based
 * procedure. In each round, each senator can exercise one of the two rights:
 * - Ban one senator's right: A senator can make another senator lose all his rights in
 *   this and all the following rounds.
 * - Announce the victory: If this senator found the senators who still have rights to
 *   vote are all from the same party, he can announce the victory and decide on the
 *   change in the game.
 *
 * Given a string senate representing each senator's party belonging. The character 'R'
 * and 'D' represent the Radiant party and the Dire party. Then if there are n senators,
 * the size of the given string will be n.
 *
 * The round-based procedure starts from the first senator to the last senator in the
 * given order. This procedure will last until the end of voting. All the senators who
 * have lost their rights will be skipped during the procedure.
 *
 * Suppose every senator is smart enough and will play the best strategy for his own
 * party. Predict which party will finally announce the victory and change the Dota2
 * game. The output should be "Radiant" or "Dire".
*/

/**
 * @param {string} senate
 * @return {string}
 */
var predictPartyVictory = function(senate) {
  const rQueue = [];
  const dQueue = [];

  for (let i = 0; i < senate.length; i++) {
    if (senate[i] === 'R') rQueue.push(i);
    else dQueue.push(i);
  }

  while (rQueue.length && dQueue.length) {
    const [rIndex, dIndex] = [rQueue.shift(), dQueue.shift()];
    if (rIndex < dIndex) {
      rQueue.push(rIndex + senate.length);
    } else {
      dQueue.push(dIndex + senate.length);
    }
  }

  return rQueue.length > 0 ? 'Radiant' : 'Dire';
};