日常水题（腾讯秋招50道）

Author: programmerhjh

src/myleetcode/PowerOfTwo.java

@@ -0,0 +1,18 @@
+package myleetcode;
+
+/**
+ * 2的幂
+ * @author acer
+ *
+ */
+public class PowerOfTwo {
+	
+	public static boolean isPowerOfTwo(int n) {
+        if ((n & n-1) == 0) {
+			return true;
+		} else {
+			return false;
+		}
+    }
+	
+}

src/myleetcode/ValidParentheses.java

@@ -0,0 +1,40 @@
+package myleetcode;
+
+/**
+ * 有效的括号
+ * @author acer
+ *
+ */
+public class ValidParentheses {
+
+	public static boolean isValid(String s) {
+		s = s.trim();
+		if (s.length() == 0) {
+			return true;
+		}
+		if (s.length() % 2 == 1) {
+			return false;
+		}
+		StringBuffer buffer = new StringBuffer(s);
+		while (buffer.length() != 0) {
+			int tempLen = buffer.length();
+			for (int i = 0; i < buffer.length()-1; ) {
+				if (
+						((int) buffer.charAt(i) == 40 && (int) buffer.charAt(i+1) == 41) 
+						|| ((int) buffer.charAt(i) == 91 && (int) buffer.charAt(i+1) == 93) 
+						|| ((int) buffer.charAt(i) == 123 && (int) buffer.charAt(i+1) == 125)	
+				   ) {
+					buffer.delete(i, i+2);
+					break;
+				} else {
+					i++;
+				}
+			}
+			if (buffer.length() == tempLen && tempLen != 0) {
+				return false;
+			}
+		}
+		return true;
+    }
+	
+}