feat: add solutions to lc problems

* No.0028.Find the Index of the First Occurrence in a String
* No.0484.Find Permutation

Author: yanglbme

solution/0000-0099/0028.Implement strStr()/README.md solution/0000-0099/0028.Find the Index of the First Occurrence in a String/README.md

@@ -1,6 +1,6 @@
-# [28. 实现 strStr()](https://leetcode.cn/problems/implement-strstr)
+# [28. 实现 strStr()](https://leetcode.cn/problems/find-the-index-of-the-first-occurrence-in-a-string)
 
-[English Version](/solution/0000-0099/0028.Implement%20strStr%28%29/README_EN.md)
+[English Version](/solution/0000-0099/0028.Find%20the%20Index%20of%20the%20First%20Occurrence%20in%20a%20String/README_EN.md)
 
 ## 题目描述
 
@@ -41,6 +41,7 @@
 	<li><code>haystack</code> 和 <code>needle</code> 仅由小写英文字符组成</li>
 </ul>
 
+
 ## 解法
 
 <!-- 这里可写通用的实现逻辑 -->

solution/0000-0099/0028.Implement strStr()/README_EN.md solution/0000-0099/0028.Find the Index of the First Occurrence in a String/README_EN.md

@@ -1,32 +1,27 @@
-# [28. Implement strStr()](https://leetcode.com/problems/implement-strstr)
+# [28. Find the Index of the First Occurrence in a String](https://leetcode.com/problems/find-the-index-of-the-first-occurrence-in-a-string)
 
-[中文文档](/solution/0000-0099/0028.Implement%20strStr%28%29/README.md)
+[中文文档](/solution/0000-0099/0028.Find%20the%20Index%20of%20the%20First%20Occurrence%20in%20a%20String/README.md)
 
 ## Description
 
-<p>Implement <a href="http://www.cplusplus.com/reference/cstring/strstr/" target="_blank">strStr()</a>.</p>
-
 <p>Given two strings <code>needle</code> and <code>haystack</code>, return the index of the first occurrence of <code>needle</code> in <code>haystack</code>, or <code>-1</code> if <code>needle</code> is not part of <code>haystack</code>.</p>
 
-<p><strong>Clarification:</strong></p>
-
-<p>What should we return when <code>needle</code> is an empty string? This is a great question to ask during an interview.</p>
-
-<p>For the purpose of this problem, we will return 0 when <code>needle</code> is an empty string. This is consistent to C&#39;s <a href="http://www.cplusplus.com/reference/cstring/strstr/" target="_blank">strstr()</a> and Java&#39;s <a href="https://docs.oracle.com/javase/7/docs/api/java/lang/String.html#indexOf(java.lang.String)" target="_blank">indexOf()</a>.</p>
-
 <p>&nbsp;</p>
-<p><strong>Example 1:</strong></p>
+<p><strong class="example">Example 1:</strong></p>
 
 <pre>
-<strong>Input:</strong> haystack = &quot;hello&quot;, needle = &quot;ll&quot;
-<strong>Output:</strong> 2
+<strong>Input:</strong> haystack = &quot;sadbutsad&quot;, needle = &quot;sad&quot;
+<strong>Output:</strong> 0
+<strong>Explanation:</strong> &quot;sad&quot; occurs at index 0 and 6.
+The first occurrence is at index 0, so we return 0.
 </pre>
 
-<p><strong>Example 2:</strong></p>
+<p><strong class="example">Example 2:</strong></p>
 
 <pre>
-<strong>Input:</strong> haystack = &quot;aaaaa&quot;, needle = &quot;bba&quot;
+<strong>Input:</strong> haystack = &quot;leetcode&quot;, needle = &quot;leeto&quot;
 <strong>Output:</strong> -1
+<strong>Explanation:</strong> &quot;leeto&quot; did not occur in &quot;leetcode&quot;, so we return -1.
 </pre>
 
 <p>&nbsp;</p>
@@ -37,6 +32,7 @@
 	<li><code>haystack</code> and <code>needle</code> consist of only lowercase English characters.</li>
 </ul>
 
+
 ## Solutions
 
 <!-- tabs:start -->

solution/0000-0099/0028.Implement strStr()/Solution.cpp solution/0000-0099/0028.Find the Index of the First Occurrence in a String/Solution.cpp

@@ -46,22 +46,126 @@
 
 <!-- 这里可写通用的实现逻辑 -->
 
+**方法一：贪心**
+
+先初始化结果数组 `ans` 为 `[1, 2, 3, ..., n+1]`。
+
+假定某个连续 `D` 子数组区间为 `[i, j)`，那么只要翻转 `ans[i: j + 1]` 即可。
+
+因此，遍历字符串 `s`，找出所有的连续 `D` 子数组区间，将其翻转。
+
+时间复杂度 $O(n)$，其中 $n$ 表示字符串 `s` 的长度。
+
 <!-- tabs:start -->
 
 ### **Python3**
 
 <!-- 这里可写当前语言的特殊实现逻辑 -->
 
 ```python
-
+class Solution:
+    def findPermutation(self, s: str) -> List[int]:
+        n = len(s)
+        ans = list(range(1, n + 2))
+        i = 0
+        while i < n:
+            j = i
+            while j < n and s[j] == 'D':
+                j += 1
+            ans[i: j + 1] = ans[i: j + 1][::-1]
+            i = max(i + 1, j)
+        return ans
 ```
 
 ### **Java**
 
 <!-- 这里可写当前语言的特殊实现逻辑 -->
 
 ```java
+class Solution {
+    public int[] findPermutation(String s) {
+        int n = s.length();
+        int[] ans = new int[n + 1];
+        for (int i = 0; i < n + 1; ++i) {
+            ans[i] = i + 1;
+        }
+        int i = 0;
+        while (i < n) {
+            int j = i;
+            while (j < n && s.charAt(j) == 'D') {
+                ++j;
+            }
+            reverse(ans, i, j);
+            i = Math.max(i + 1, j);
+        }
+        return ans;
+    }
+
+    private void reverse(int[] arr, int i, int j) {
+        for (; i < j; ++i, --j) {
+            int t = arr[i];
+            arr[i] = arr[j];
+            arr[j] = t;
+        }
+    }
+}
+```
+
+### **C++**
+
+```cpp
+class Solution {
+public:
+    vector<int> findPermutation(string s) {
+        int n = s.size();
+        vector<int> ans(n + 1);
+        iota(ans.begin(), ans.end(), 1);
+        int i = 0;
+        while (i < n) {
+            int j = i;
+            while (j < n && s[j] == 'D') {
+                ++j;
+            }
+            reverse(ans.begin() + i, ans.begin() + j + 1);
+            i = max(i + 1, j);
+        }
+        return ans;
+    }
+};
+```
 
+### **Go**
+
+```go
+func findPermutation(s string) []int {
+	n := len(s)
+	ans := make([]int, n+1)
+	for i := range ans {
+		ans[i] = i + 1
+	}
+	i := 0
+	for i < n {
+		j := i
+		for ; j < n && s[j] == 'D'; j++ {
+		}
+		reverse(ans, i, j)
+		i = max(i+1, j)
+	}
+	return ans
+}
+
+func reverse(arr []int, i, j int) {
+	for ; i < j; i, j = i+1, j-1 {
+		arr[i], arr[j] = arr[j], arr[i]
+	}
+}
+
+func max(a, b int) int {
+	if a > b {
+		return a
+	}
+	return b
+}
 ```
 
 ### **...**

solution/0000-0099/0028.Implement strStr()/Solution.cs solution/0000-0099/0028.Find the Index of the First Occurrence in a String/Solution.cs

@@ -45,13 +45,107 @@
 ### **Python3**
 
 ```python
-
+class Solution:
+    def findPermutation(self, s: str) -> List[int]:
+        n = len(s)
+        ans = list(range(1, n + 2))
+        i = 0
+        while i < n:
+            j = i
+            while j < n and s[j] == 'D':
+                j += 1
+            ans[i: j + 1] = ans[i: j + 1][::-1]
+            i = max(i + 1, j)
+        return ans
 ```
 
 ### **Java**
 
 ```java
+class Solution {
+    public int[] findPermutation(String s) {
+        int n = s.length();
+        int[] ans = new int[n + 1];
+        for (int i = 0; i < n + 1; ++i) {
+            ans[i] = i + 1;
+        }
+        int i = 0;
+        while (i < n) {
+            int j = i;
+            while (j < n && s.charAt(j) == 'D') {
+                ++j;
+            }
+            reverse(ans, i, j);
+            i = Math.max(i + 1, j);
+        }
+        return ans;
+    }
+
+    private void reverse(int[] arr, int i, int j) {
+        for (; i < j; ++i, --j) {
+            int t = arr[i];
+            arr[i] = arr[j];
+            arr[j] = t;
+        }
+    }
+}
+```
+
+### **C++**
+
+```cpp
+class Solution {
+public:
+    vector<int> findPermutation(string s) {
+        int n = s.size();
+        vector<int> ans(n + 1);
+        iota(ans.begin(), ans.end(), 1);
+        int i = 0;
+        while (i < n) {
+            int j = i;
+            while (j < n && s[j] == 'D') {
+                ++j;
+            }
+            reverse(ans.begin() + i, ans.begin() + j + 1);
+            i = max(i + 1, j);
+        }
+        return ans;
+    }
+};
+```
 
+### **Go**
+
+```go
+func findPermutation(s string) []int {
+	n := len(s)
+	ans := make([]int, n+1)
+	for i := range ans {
+		ans[i] = i + 1
+	}
+	i := 0
+	for i < n {
+		j := i
+		for ; j < n && s[j] == 'D'; j++ {
+		}
+		reverse(ans, i, j)
+		i = max(i+1, j)
+	}
+	return ans
+}
+
+func reverse(arr []int, i, j int) {
+	for ; i < j; i, j = i+1, j-1 {
+		arr[i], arr[j] = arr[j], arr[i]
+	}
+}
+
+func max(a, b int) int {
+	if a > b {
+		return a
+	}
+	return b
+}
 ```
 
 ### **...**

solution/0000-0099/0028.Implement strStr()/Solution.go solution/0000-0099/0028.Find the Index of the First Occurrence in a String/Solution.go

@@ -0,0 +1,18 @@
+class Solution {
+public:
+    vector<int> findPermutation(string s) {
+        int n = s.size();
+        vector<int> ans(n + 1);
+        iota(ans.begin(), ans.end(), 1);
+        int i = 0;
+        while (i < n) {
+            int j = i;
+            while (j < n && s[j] == 'D') {
+                ++j;
+            }
+            reverse(ans.begin() + i, ans.begin() + j + 1);
+            i = max(i + 1, j);
+        }
+        return ans;
+    }
+};

solution/0000-0099/0028.Implement strStr()/Solution.java solution/0000-0099/0028.Find the Index of the First Occurrence in a String/Solution.java

@@ -0,0 +1,29 @@
+func findPermutation(s string) []int {
+	n := len(s)
+	ans := make([]int, n+1)
+	for i := range ans {
+		ans[i] = i + 1
+	}
+	i := 0
+	for i < n {
+		j := i
+		for ; j < n && s[j] == 'D'; j++ {
+		}
+		reverse(ans, i, j)
+		i = max(i+1, j)
+	}
+	return ans
+}
+
+func reverse(arr []int, i, j int) {
+	for ; i < j; i, j = i+1, j-1 {
+		arr[i], arr[j] = arr[j], arr[i]
+	}
+}
+
+func max(a, b int) int {
+	if a > b {
+		return a
+	}
+	return b
+}

solution/0000-0099/0028.Implement strStr()/Solution.js solution/0000-0099/0028.Find the Index of the First Occurrence in a String/Solution.js

@@ -0,0 +1,27 @@
+class Solution {
+    public int[] findPermutation(String s) {
+        int n = s.length();
+        int[] ans = new int[n + 1];
+        for (int i = 0; i < n + 1; ++i) {
+            ans[i] = i + 1;
+        }
+        int i = 0;
+        while (i < n) {
+            int j = i;
+            while (j < n && s.charAt(j) == 'D') {
+                ++j;
+            }
+            reverse(ans, i, j);
+            i = Math.max(i + 1, j);
+        }
+        return ans;
+    }
+
+    private void reverse(int[] arr, int i, int j) {
+        for (; i < j; ++i, --j) {
+            int t = arr[i];
+            arr[i] = arr[j];
+            arr[j] = t;
+        }
+    }
+}

solution/0000-0099/0028.Implement strStr()/Solution.py solution/0000-0099/0028.Find the Index of the First Occurrence in a String/Solution.py

@@ -0,0 +1,12 @@
+class Solution:
+    def findPermutation(self, s: str) -> List[int]:
+        n = len(s)
+        ans = list(range(1, n + 2))
+        i = 0
+        while i < n:
+            j = i
+            while j < n and s[j] == 'D':
+                j += 1
+            ans[i: j + 1] = ans[i: j + 1][::-1]
+            i = max(i + 1, j)
+        return ans