Update 0242: Add C solution

problems/0242.有效的字母异位词.md

@@ -383,6 +383,31 @@ object Solution {
     }
 ```
 
+### C
+
+```c
+bool isAnagram(char* s, char* t) {
+    int len1 = strlen(s), len2 = strlen(t);
+    if (len1 != len2) {
+        return false;
+    }
+
+    int map1[26] = {0}, map2[26] = {0};
+    for (int i = 0; i < len1; i++) {
+        map1[s[i] - 'a'] += 1;
+        map2[t[i] - 'a'] += 1;
+    }
+    
+    for (int i = 0; i < 26; i++) {
+        if (map1[i] != map2[i]) {
+            return false;
+        }
+    }
+    
+    return true;
+}
+```
+
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