Create 1647-minimum-deletions-to-make-character-frequencies-unique.js

Author: aadil42

javascript/1647-minimum-deletions-to-make-character-frequencies-unique.js

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+/**
+ * Hasing
+ * Time O(n) | Space O(n)
+ * https://leetcode.com/problems/minimum-deletions-to-make-character-frequencies-unique/
+ * @param {string} s
+ * @return {number}
+ */
+var minDeletions = function(s) {
+    
+    // hash frequency
+    let i = 0;
+    const charHash = new Map();
+    while(i < s.length)  {
+        const frequency = charHash.get(s[i]) || 0;
+        charHash.set(s[i], frequency+1);
+        i++;
+    }
+    const frequencyHash = new Map();
+    for(const [key, val] of charHash) {
+        const frequency = frequencyHash.get(val) || 0;
+        frequencyHash.set(val, frequency+1);
+    }
+
+    let min = 0;
+    for(const [key, val] of frequencyHash) {
+        let frequency = key;
+        let frequencyOfFrequency = val;
+        while(frequencyOfFrequency > 1) {
+            while(frequencyHash.has(frequency)) {
+                frequency -= 1;
+                min += 1;
+            }
+            if(frequency > 0) frequencyHash.set(frequency, 1);
+            frequency = key;
+            frequencyOfFrequency -= 1;
+        }
+    }
+    return min;
+};