sort-characters-by-frequency solution java

sort-characters-by-frequency/Solution.java

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+// Accepted
+// Runtime: 10 ms
+// Memory Usage: 40 MB
+// Submitted: January 14th, 2021
+
+class Solution {
+    public String frequencySort(String s) {
+        // Get each character's frequency
+        Map<Character, Integer> count = new HashMap<Character, Integer>();
+        for (char c : s.toCharArray())
+            count.put(c, count.getOrDefault(c, 0) + 1);
+        
+        // Paired with the character, sort each frequency
+        PriorityQueue<Map.Entry<Character, Integer>> pq = new PriorityQueue<>((a, b) -> b.getValue() - a.getValue());
+        pq.addAll(count.entrySet());
+        
+        // Building the final st
+        StringBuilder sb = new StringBuilder();
+        while (!pq.isEmpty()) {
+            Map.Entry entry = pq.poll();
+            char v = (char) entry.getKey();
+            int n = (int) entry.getValue();
+            
+            // Place n many v chars in the StringBuilder
+            for (int i = 0; i < n; i++)
+                sb.append(v);
+        }
+        
+        return sb.toString();
+    }
+}