506. Relative Ranks

Problem

You are given an integer array score of size n, where score[i] is the score of the ith athlete in a competition. All the scores are guaranteed to be unique.

The athletes are placed based on their scores, where the 1st place athlete has the highest score, the 2nd place athlete has the 2nd highest score, and so on. The placement of each athlete determines their rank:

• The 1st place athlete's rank is "Gold Medal".
• The 2nd place athlete's rank is "Silver Medal".
• The 3rd place athlete's rank is "Bronze Medal".
• For the 4th place to the nth place athlete, their rank is their placement number (i.e., the xth place athlete's rank is "x").

Return an array answer of size n where answer[i] is the rank of the ith athlete.

Example 1:

Input: score = [5,4,3,2,1]
Output: ["Gold Medal","Silver Medal","Bronze Medal","4","5"]
Explanation: The placements are [1st, 2nd, 3rd, 4th, 5th].

Example 2:

Input: score = [10,3,8,9,4]
Output: ["Gold Medal","5","Bronze Medal","Silver Medal","4"]
Explanation: The placements are [1st, 5th, 3rd, 2nd, 4th].

Constraints:

• n == score.length
• 1 <= n <= 10000
• 0 <= score[i] <= 1000000
• All the values in score are unique.

Problem Summary

You are given an integer array score of length n, where score[i] is the score of the ith athlete in a competition. All scores are unique.

The athletes are ranked according to their scores, where the athlete ranked 1st has the highest score, the athlete ranked 2nd has the 2nd highest score, and so on. An athlete's rank determines their award:

• The athlete ranked 1st receives the gold medal "Gold Medal".
• The athlete ranked 2nd receives the silver medal "Silver Medal".
• The athlete ranked 3rd receives the bronze medal "Bronze Medal".
• Athletes ranked from 4th to nth receive only their rank number (i.e., the athlete ranked xth receives the number "x").

Return the awards using an array answer of length n, where answer[i] is the award of the ith athlete.

Solution Approach

• Use a map to record the original index corresponding to each element in score, then sort score. For the sorted elements, we can use the map to know their ranks.

Code

package leetcode

import (
	"sort"
	"strconv"
)

func findRelativeRanks(score []int) []string {
	mp := make(map[int]int)
	for i, v := range score {
		mp[v] = i
	}
	sort.Slice(score, func(i, j int) bool {
		return score[i] > score[j]
	})
	ans := make([]string, len(score))
	for i, v := range score {
		if i == 0 {
			ans[mp[v]] = "Gold Medal"
		} else if i == 1 {
			ans[mp[v]] = "Silver Medal"
		} else if i == 2 {
			ans[mp[v]] = "Bronze Medal"
		} else {
			ans[mp[v]] = strconv.Itoa(i + 1)
		}
	}
	return ans
}