Merge pull request #488 from evandronmota/master

Add LeetCode 231

leetcode/README.md

@@ -52,7 +52,9 @@ LeetCode
 |215|[Kth Largest Element in an Array](https://leetcode.com/problems/kth-largest-element-in-an-array/) | [C](./src/215.c)|Medium|
 |217|[Contains Duplicate](https://leetcode.com/problems/contains-duplicate/) | [C](./src/217.c)|Easy|
 |226|[Invert Binary Tree](https://leetcode.com/problems/invert-binary-tree/) | [C](./src/226.c)|Easy|
+|231|[Power of Two](https://leetcode.com/problems/power-of-two/) | [C](./src/231.c)|Easy|
 |234|[Palindrome Linked List](https://leetcode.com/problems/palindrome-linked-list/) | [C](./src/234.c)|Easy|
+|242|[Valid Anagram](https://leetcode.com/problems/valid-anagram/) | [C](./src/242.c)|Easy|
 |268|[Missing Number](https://leetcode.com/problems/missing-number/) | [C](./src/268.c)|Easy|
 |278|[First Bad Version](https://leetcode.com/problems/first-bad-version/) | [C](./src/278.c)|Easy|
 |283|[Move Zeroes](https://leetcode.com/problems/move-zeroes/) | [C](./src/283.c)|Easy|

leetcode/src/231.c

@@ -0,0 +1,5 @@
+bool isPowerOfTwo(int n){
+    if (! n) return false;
+    while (n % 2 == 0) n /= 2;
+    return n == 1;
+}

leetcode/src/242.c

@@ -0,0 +1,20 @@
+bool isAnagram(char * s, char * t){
+    int n = strlen(s);
+    int m = strlen(t);
+    
+    int cnt_s[1000], cnt_t[1000];
+    for (int c = 97; c < 97 + 26; c++)
+        cnt_s[c] = cnt_t[c] = 0;
+
+    for (int i = 0; i < n; i++)
+        cnt_s[s[i]]++;
+    
+    for (int i = 0; i < m; i++)
+        cnt_t[t[i]]++;
+    
+    for (int c = 97; c < 97 + 26; c++)
+        if (cnt_s[c] != cnt_t[c])
+            return false;
+
+    return true;
+}