1331. Rank Transform of an Array.cpp

// 1331. Rank Transform of an Array
// Solved
// Easy
// Topics
// Companies
// Hint
// Given an array of integers arr, replace each element with its rank.

// The rank represents how large the element is. The rank has the following rules:

// Rank is an integer starting from 1.
// The larger the element, the larger the rank. If two elements are equal, their rank must be the same.
// Rank should be as small as possible.
 

// Example 1:

// Input: arr = [40,10,20,30]
// Output: [4,1,2,3]
// Explanation: 40 is the largest element. 10 is the smallest. 20 is the second smallest. 30 is the third smallest.
// Example 2:

// Input: arr = [100,100,100]
// Output: [1,1,1]
// Explanation: Same elements share the same rank.
// Example 3:

// Input: arr = [37,12,28,9,100,56,80,5,12]
// Output: [5,3,4,2,8,6,7,1,3]
 

// Constraints:

// 0 <= arr.length <= 105
// -109 <= arr[i] <= 109

// Seen this question in a real interview before?
// 1/5

class Solution {
public:
    vector<int> arrayRankTransform(vector<int>& arr) {
        unordered_map<int,int>numToRank;
        set<int>nums(arr.begin(),arr.end());
        int rank=1;
        for(auto num:nums){
            numToRank[num]=rank;
            rank++;
        }
        for(int i=0;i<arr.size();i++){
            arr[i]=numToRank[arr[i]];
        }
        return arr;
    }
};
 static const int __ = [](){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    return 0;
}();