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Commit b4daf1d

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feat: add solutions to leetcode problem: No.0451. Sort Characters By Frequency
1 parent 61a49b0 commit b4daf1d

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4 files changed

+137
-6
lines changed

4 files changed

+137
-6
lines changed

‎solution/0400-0499/0451.Sort Characters By Frequency/README.md‎

Lines changed: 47 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -50,27 +50,71 @@
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注意'A'和'a'被认为是两种不同的字符。
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</pre>
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## 解法
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<!-- 这里可写通用的实现逻辑 -->
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"计数器 + 桶"实现。其中,计数器统计字符串中每个字符出现的次数。而对于桶,第 i 个位置存放出现次数为 i 的所有字符。
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<!-- tabs:start -->
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### **Python3**
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```python
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class Solution:
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def frequencySort(self, s: str) -> str:
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if not s or len(s) < 3:
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return s
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counter = collections.Counter(s)
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buckets = [[] for _ in range(len(s) + 1)]
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for c, count in counter.items():
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buckets[count].append(c)
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res = []
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for i in range(len(s), -1, -1):
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if buckets[i]:
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for c in buckets[i]:
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res.append(c * i)
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return ''.join(res)
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```
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### **Java**
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```java
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class Solution {
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public String frequencySort(String s) {
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if (s == null || s.length() < 3) {
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return s;
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}
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Map<Character, Integer> counter = new HashMap<>();
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for (int i = 0; i < s.length(); ++i) {
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counter.put(s.charAt(i), counter.getOrDefault(s.charAt(i), 0) + 1);
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}
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List<Character>[] buckets = new List[s.length() + 1];
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for (Map.Entry<Character, Integer> entry : counter.entrySet()) {
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char c = entry.getKey();
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int count = entry.getValue();
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if (buckets[count] == null) {
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buckets[count] = new ArrayList<>();
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}
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buckets[count].add(c);
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}
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StringBuilder sb = new StringBuilder();
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for (int i = s.length(); i >= 0; --i) {
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if (buckets[i] != null) {
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for (char c : buckets[i]) {
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for (int j = 0; j < i; ++j) {
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sb.append(c);
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}
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}
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}
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}
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return sb.toString();
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}
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}
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```
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### **...**

‎solution/0400-0499/0451.Sort Characters By Frequency/README_EN.md‎

Lines changed: 45 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -42,21 +42,63 @@ Note that &#39;A&#39; and &#39;a&#39; are treated as two different characters.
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<li><code>s</code> consists of English letters and digits.</li>
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</ul>
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## Solutions
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<!-- tabs:start -->
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### **Python3**
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```python
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class Solution:
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def frequencySort(self, s: str) -> str:
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if not s or len(s) < 3:
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return s
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counter = collections.Counter(s)
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buckets = [[] for _ in range(len(s) + 1)]
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for c, count in counter.items():
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buckets[count].append(c)
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res = []
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for i in range(len(s), -1, -1):
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if buckets[i]:
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for c in buckets[i]:
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res.append(c * i)
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return ''.join(res)
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```
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### **Java**
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```java
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class Solution {
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public String frequencySort(String s) {
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if (s == null || s.length() < 3) {
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return s;
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}
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Map<Character, Integer> counter = new HashMap<>();
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for (int i = 0; i < s.length(); ++i) {
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counter.put(s.charAt(i), counter.getOrDefault(s.charAt(i), 0) + 1);
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}
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List<Character>[] buckets = new List[s.length() + 1];
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for (Map.Entry<Character, Integer> entry : counter.entrySet()) {
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char c = entry.getKey();
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int count = entry.getValue();
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if (buckets[count] == null) {
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buckets[count] = new ArrayList<>();
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}
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buckets[count].add(c);
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}
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StringBuilder sb = new StringBuilder();
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for (int i = s.length(); i >= 0; --i) {
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if (buckets[i] != null) {
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for (char c : buckets[i]) {
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for (int j = 0; j < i; ++j) {
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sb.append(c);
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}
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}
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}
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}
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return sb.toString();
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}
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}
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```
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### **...**
Lines changed: 31 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,31 @@
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class Solution {
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public String frequencySort(String s) {
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if (s == null || s.length() < 3) {
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return s;
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}
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Map<Character, Integer> counter = new HashMap<>();
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for (int i = 0; i < s.length(); ++i) {
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counter.put(s.charAt(i), counter.getOrDefault(s.charAt(i), 0) + 1);
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}
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List<Character>[] buckets = new List[s.length() + 1];
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for (Map.Entry<Character, Integer> entry : counter.entrySet()) {
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char c = entry.getKey();
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int count = entry.getValue();
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if (buckets[count] == null) {
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buckets[count] = new ArrayList<>();
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}
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buckets[count].add(c);
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}
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StringBuilder sb = new StringBuilder();
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for (int i = s.length(); i >= 0; --i) {
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if (buckets[i] != null) {
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for (char c : buckets[i]) {
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for (int j = 0; j < i; ++j) {
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sb.append(c);
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}
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}
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}
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}
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return sb.toString();
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}
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}
Lines changed: 14 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,14 @@
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class Solution:
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def frequencySort(self, s: str) -> str:
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if not s or len(s) < 3:
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return s
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counter = collections.Counter(s)
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buckets = [[] for _ in range(len(s) + 1)]
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for c, count in counter.items():
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buckets[count].append(c)
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res = []
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for i in range(len(s), -1, -1):
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if buckets[i]:
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for c in buckets[i]:
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res.append(c * i)
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return ''.join(res)

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