feat: add solutions to lc problem: No.0125. Valid Palindrome

Author: yanglbme

images/contributors.svg

@@ -22,7 +22,6 @@
 <strong>输出:</strong> false
 </pre>
 
-
 ## 解法
 
 <!-- 这里可写通用的实现逻辑 -->
@@ -34,15 +33,74 @@
 <!-- 这里可写当前语言的特殊实现逻辑 -->
 
 ```python
-
+class Solution:
+    def isPalindrome(self, s: str) -> bool:
+        i, j = 0, len(s) - 1
+        while i < j:
+            if not s[i].isalnum():
+                i += 1
+            elif not s[j].isalnum():
+                j -= 1
+            elif s[i].lower() != s[j].lower():
+                return False
+            else:
+                i += 1
+                j -= 1
+        return True
 ```
 
 ### **Java**
 
 <!-- 这里可写当前语言的特殊实现逻辑 -->
 
 ```java
+class Solution {
+    public boolean isPalindrome(String s) {
+        int i = 0, j = s.length() - 1;
+        while (i < j) {
+            if (!Character.isLetterOrDigit(s.charAt(i))) {
+                ++i;
+            } else if (!Character.isLetterOrDigit(s.charAt(j))) {
+                --j;
+            } else if (Character.toUpperCase(s.charAt(i)) != Character.toUpperCase(s.charAt(j))) {
+                return false;
+            } else {
+                ++i;
+                --j;
+            }
+        }
+        return true;
+    }
+}
+```
 
+### **C++**
+
+```cpp
+class Solution {
+public:
+    bool isPalindrome(string s) {
+        int i = 0, j = s.size() - 1;
+        while (i < j) {
+            if (!isAlphaNum(s[i])) ++i;
+            else if (!isAlphaNum(s[j])) --j;
+            else if ((s[i] + 32 - 'a') % 32 != (s[j] + 32 - 'a') % 32) return false;
+            else {
+                ++i;
+                --j;
+            }
+        }
+        return true;
+    }
+
+private:
+    bool isAlphaNum(char &ch) {
+        if (ch >= 'a' && ch <= 'z') return true;
+        if (ch >= 'A' && ch <= 'Z') return true;
+        if (ch >= '0' && ch <= '9') return true;
+        return false;
+    }
+};
 ```
 
 ### **...**

solution/0100-0199/0125.Valid Palindrome/README.md

@@ -31,21 +31,79 @@
 	<li><code>s</code> consists only of printable ASCII characters.</li>
 </ul>
 
-
 ## Solutions
 
 <!-- tabs:start -->
 
 ### **Python3**
 
 ```python
-
+class Solution:
+    def isPalindrome(self, s: str) -> bool:
+        i, j = 0, len(s) - 1
+        while i < j:
+            if not s[i].isalnum():
+                i += 1
+            elif not s[j].isalnum():
+                j -= 1
+            elif s[i].lower() != s[j].lower():
+                return False
+            else:
+                i += 1
+                j -= 1
+        return True
 ```
 
 ### **Java**
 
 ```java
+class Solution {
+    public boolean isPalindrome(String s) {
+        int i = 0, j = s.length() - 1;
+        while (i < j) {
+            if (!Character.isLetterOrDigit(s.charAt(i))) {
+                ++i;
+            } else if (!Character.isLetterOrDigit(s.charAt(j))) {
+                --j;
+            } else if (Character.toUpperCase(s.charAt(i)) != Character.toUpperCase(s.charAt(j))) {
+                return false;
+            } else {
+                ++i;
+                --j;
+            }
+        }
+        return true;
+    }
+}
+```
 
+### **C++**
+
+```cpp
+class Solution {
+public:
+    bool isPalindrome(string s) {
+        int i = 0, j = s.size() - 1;
+        while (i < j) {
+            if (!isAlphaNum(s[i])) ++i;
+            else if (!isAlphaNum(s[j])) --j;
+            else if ((s[i] + 32 - 'a') % 32 != (s[j] + 32 - 'a') % 32) return false;
+            else {
+                ++i;
+                --j;
+            }
+        }
+        return true;
+    }
+
+private:
+    bool isAlphaNum(char &ch) {
+        if (ch >= 'a' && ch <= 'z') return true;
+        if (ch >= 'A' && ch <= 'Z') return true;
+        if (ch >= '0' && ch <= '9') return true;
+        return false;
+    }
+};
 ```
 
 ### **...**

solution/0100-0199/0125.Valid Palindrome/README_EN.md

@@ -1,14 +1,14 @@
 class Solution {
 public:
     bool isPalindrome(string s) {
-        int left = 0, right = s.size() - 1;
-        while (left < right) {
-            if (!isAlphaNum(s[left])) ++left;
-            else if (!isAlphaNum(s[right])) --right;
-            else if ((s[left] + 32 - 'a') % 32 != (s[right] + 32 - 'a') % 32) return false;
+        int i = 0, j = s.size() - 1;
+        while (i < j) {
+            if (!isAlphaNum(s[i])) ++i;
+            else if (!isAlphaNum(s[j])) --j;
+            else if ((s[i] + 32 - 'a') % 32 != (s[j] + 32 - 'a') % 32) return false;
             else {
-                ++left;
-                --right;
+                ++i;
+                --j;
             }
         }
         return true;

solution/0100-0199/0125.Valid Palindrome/Solution.cpp

@@ -1,19 +1,17 @@
 class Solution {
     public boolean isPalindrome(String s) {
-        int i = 0;
-        int j = s.length() - 1;
+        int i = 0, j = s.length() - 1;
         while (i < j) {
-            while (i < j && !Character.isLetterOrDigit(s.charAt(i))) {
-                i++;
-            }
-            while (i < j && !Character.isLetterOrDigit(s.charAt(j))) {
-                j--;
-            }
-            if (i < j && Character.toUpperCase(s.charAt(i)) != Character.toUpperCase(s.charAt(j))) {
+            if (!Character.isLetterOrDigit(s.charAt(i))) {
+                ++i;
+            } else if (!Character.isLetterOrDigit(s.charAt(j))) {
+                --j;
+            } else if (Character.toUpperCase(s.charAt(i)) != Character.toUpperCase(s.charAt(j))) {
                 return false;
+            } else {
+                ++i;
+                --j;
             }
-            i++;
-            j--;
         }
         return true;
     }