climbingLeaderboard hackerrank

climbingLeaderboard.js

function climbingLeaderboard(scores, alice) {
    const uniqueScores = [...new Set(scores)]; //for removing duplicate entries.
    let preIndex = uniqueScores.length,        //starting position of nested loop.
        rank = uniqueScores.length + 1,        //last rank default.
        aliceRanks = [];

    for(let i = 0; i < alice.length; i++){
      let s = preIndex;
      for(s; s--;){
        if(alice[i] < uniqueScores[s]){
          aliceRanks.push(rank);
          preIndex = s + 1;                    //update nested loop's starting position, so ignore previously checked elements.
          break;                               //break the loop.
        }
        else rank -= 1;                       //Hurry got big score, just update the rank.
      }
      s < 0 && aliceRanks.push(1);            //Hurry no more competitor, got 1st position.
    }
    return aliceRanks;
  }