feat: update solutions to lc problem: No.0451. Sort Characters By Frequency

yanglbme · yanglbme · commit 5d9312731ca6 · 2021-07-03T22:15:56.000+08:00
diff --git a/solution/0400-0499/0451.Sort Characters By Frequency/README.md b/solution/0400-0499/0451.Sort Characters By Frequency/README.md
@@ -65,10 +65,8 @@
 ```python
 class Solution:
     def frequencySort(self, s: str) -> str:
-        if not s or len(s) < 3:
-            return s
         counter = collections.Counter(s)
-        buckets = [[] for _ in range(len(s) + 1)]
+        buckets = collections.defaultdict(list)
         for c, freq in counter.items():
             buckets[freq].append(c)
         res = []
@@ -86,12 +84,9 @@ class Solution:
 ```java
 class Solution {
     public String frequencySort(String s) {
-        if (s == null || s.length() < 3) {
-            return s;
-        }
         Map<Character, Integer> counter = new HashMap<>();
-        for (int i = 0; i < s.length(); ++i) {
-            counter.put(s.charAt(i), counter.getOrDefault(s.charAt(i), 0) + 1);
+        for (char c : s.toCharArray()) {
+            counter.put(c, counter.getOrDefault(c, 0) + 1);
         }
         List<Character>[] buckets = new List[s.length() + 1];
         for (Map.Entry<Character, Integer> entry : counter.entrySet()) {
diff --git a/solution/0400-0499/0451.Sort Characters By Frequency/README_EN.md b/solution/0400-0499/0451.Sort Characters By Frequency/README_EN.md
@@ -51,10 +51,8 @@ Note that &#39;A&#39; and &#39;a&#39; are treated as two different characters.
 ```python
 class Solution:
     def frequencySort(self, s: str) -> str:
-        if not s or len(s) < 3:
-            return s
         counter = collections.Counter(s)
-        buckets = [[] for _ in range(len(s) + 1)]
+        buckets = collections.defaultdict(list)
         for c, freq in counter.items():
             buckets[freq].append(c)
         res = []
@@ -70,12 +68,9 @@ class Solution:
 ```java
 class Solution {
     public String frequencySort(String s) {
-        if (s == null || s.length() < 3) {
-            return s;
-        }
         Map<Character, Integer> counter = new HashMap<>();
-        for (int i = 0; i < s.length(); ++i) {
-            counter.put(s.charAt(i), counter.getOrDefault(s.charAt(i), 0) + 1);
+        for (char c : s.toCharArray()) {
+            counter.put(c, counter.getOrDefault(c, 0) + 1);
         }
         List<Character>[] buckets = new List[s.length() + 1];
         for (Map.Entry<Character, Integer> entry : counter.entrySet()) {
diff --git a/solution/0400-0499/0451.Sort Characters By Frequency/Solution.java b/solution/0400-0499/0451.Sort Characters By Frequency/Solution.java
@@ -1,11 +1,8 @@
 class Solution {
     public String frequencySort(String s) {
-        if (s == null || s.length() < 3) {
-            return s;
-        }
         Map<Character, Integer> counter = new HashMap<>();
-        for (int i = 0; i < s.length(); ++i) {
-            counter.put(s.charAt(i), counter.getOrDefault(s.charAt(i), 0) + 1);
+        for (char c : s.toCharArray()) {
+            counter.put(c, counter.getOrDefault(c, 0) + 1);
         }
         List<Character>[] buckets = new List[s.length() + 1];
         for (Map.Entry<Character, Integer> entry : counter.entrySet()) {
diff --git a/solution/0400-0499/0451.Sort Characters By Frequency/Solution.py b/solution/0400-0499/0451.Sort Characters By Frequency/Solution.py
@@ -1,9 +1,7 @@
 class Solution:
     def frequencySort(self, s: str) -> str:
-        if not s or len(s) < 3:
-            return s
         counter = collections.Counter(s)
-        buckets = [[] for _ in range(len(s) + 1)]
+        buckets = collections.defaultdict(list)
         for c, freq in counter.items():
             buckets[freq].append(c)
         res = []
