May 22 ques

Author: Rishab Mehra

MayLeetCodingChallenge_2020/Sort_Characters_By_Frequency.cpp

@@ -0,0 +1,31 @@
+//https://leetcode.com/explore/challenge/card/may-leetcoding-challenge/537/week-4-may-22nd-may-28th/3337/
+
+class Solution {
+public:
+    static bool sortbysecdesc (const pair<int,int> &a, const pair<int,int> &b) { 
+        return (a.second > b.second); 
+    }
+    
+    string frequencySort(string s) {
+        map<int, int> charFreqMap;
+        int i;
+        for(i = 0; i < s.size(); i++) {
+            if(charFreqMap.find(s[i]) == charFreqMap.end())
+                charFreqMap[s[i]] = 0;
+            charFreqMap[s[i]]++;
+        }
+        vector<pair<int, int>> transformVector;
+        
+        copy(charFreqMap.begin(), charFreqMap.end(), back_inserter(transformVector));
+        
+        sort(transformVector.begin(), transformVector.end(), sortbysecdesc); 
+        
+        string ans = "";
+        for(i = 0; i < transformVector.size(); i++) {
+            pair<int, int> p = transformVector[i];
+            for(int j = 0; j < p.second; j++) 
+                ans += p.first;
+        }
+        return ans;
+    }
+};