Description：
Given scores of N athletes, find their relative ranks and the people with the top three highest scores, who will be awarded medals: “Gold Medal”, “Silver Medal” and “Bronze Medal”.

Example 1:

Input: [5, 4, 3, 2, 1]
Output: ["Gold Medal", "Silver Medal", "Bronze Medal", "4", "5"]
Explanation: The first three athletes got the top three highest scores, so they got "Gold Medal", "Silver Medal" and "Bronze Medal". 
For the left two athletes, you just need to output their relative ranks according to their scores.

Note:

• N is a positive integer and won’t exceed 10,000.
• All the scores of athletes are guaranteed to be unique.

题意：给定一个一维数组，每个元素表示了一位运动员的得分（得分越高表示排名越高），对应数组的下标位置，输出当前下标位置处的运动员的排名，对于前三名分别输出"Gold Medal"， “Silver Medal”和"Bronze Medal"；

解法：要知道每个运动员的排名，我们需要对得分的数组进行排序，这样我们就知道每个分数所对应的名次（每个运动员的得分都是不相同的），以得分和名次为键值对构建哈希表；之后，我们遍历给定的数组，由分数从哈希表中得到其排名，根据名次我们返回不同的字符串；

Java

class Solution {
    public String[] findRelativeRanks(int[] nums) {
        int[] sortNums = nums.clone();
        String[] result = new String[nums.length];
        Map<Integer, Integer> rank = new HashMap<>();
        Arrays.sort(sortNums);
        for (int i = 0; i < sortNums.length; i++) {
            rank.put(sortNums[i], sortNums.length - i);
        }
        for (int i = 0; i < nums.length; i++) {
            switch(rank.get(nums[i])) {
                case 1: 
                    result[i] = "Gold Medal";
                    break;
                case 2:
                    result[i] = "Silver Medal";
                    break;
                case 3:
                    result[i] = "Bronze Medal";
                    break;
                default:
                    result[i] = "" + rank.get(nums[i]);
            }
        }
        return result;
    }
}