365 day challenge leetcode 1000 questions - day 042 array sequence number conversion + relative ranking discretization processing

The idea of discretization

This article Well said , The core is to use hash table to reorder

1331. Array number conversion

Code implementation （ Self solution ）

class Solution {
    
public:
    vector<int> arrayRankTransform(vector<int>& arr) {
    
        vector<int> other = arr;
        unordered_map<int, int> _map;
        sort(other.begin(), other.end());
        for (int i = 0; i < other.size(); i++) {
    
           if (!_map.count(other[i])) {
    
               _map[other[i]] = _map.size() + 1;
            }
       }
       for (int& num : arr) {
    
           num = _map[num];
        }
        return arr;
    }
};

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506. Relative rank

Code implementation （ Self solution ）

class Solution {
    
public:
    vector<string> findRelativeRanks(vector<int>& score) {
    
        vector<int> ref = score;
        unordered_map<int, int> _map;
        vector<string> ans;
        sort(ref.begin(), ref.end(), greater<int>());
        for (int i = 0; i < ref.size(); i++) {
    
           _map[ref[i]] = _map.size() + 1;
        }
        for (int candidate : score) {
    
            switch(_map[candidate]) {
    
                case 1:
                ans.push_back("Gold Medal");
                break;
                case 2:
                ans.push_back("Silver Medal");
                break;
                case 3:
                ans.push_back("Bronze Medal");
                break;
                default:
                ans.push_back(to_string(_map[candidate]));
            }
        }
        return ans;
    }
};

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