climbingLeaderboard.js

Rahman Niftaliyev

This code retrieves the best rank for a given score from a sorted list of unique scores. The ranks are returned as an array of integers.

function climbingLeaderboard(scores, alice) {
  let result = [];
  let uniqueScores = [...new Set(scores)];
for (const score of alice) {
    if (score >= uniqueScores[0]) {
      result.push(1);
    } else if (score < uniqueScores[uniqueScores.length - 1]) {
      result.push(uniqueScores.length + 1);
    } else {
      result.push(rankBinarySearch(score, uniqueScores));
    }
  }
  return result;
}
function rankBinarySearch(score, uniqueScores) {
  let start = 0;
  let end = uniqueScores.length - 1;
while (true) {
    let mid = Math.floor((start + end) / 2);
// base cases
    if (uniqueScores[mid] === score) {
      return mid + 1;
    } else if (uniqueScores[mid] > score && uniqueScores[mid + 1] < score) {
      return mid + 2;
    } else if (uniqueScores[mid] < score && uniqueScores[mid - 1 > score]) {
      return mid - 1;
    }
// recursion
    if (score < uniqueScores[mid]) {
      start = mid + 1;
    } else {
      end = mid - 1;
    }
  }
}