package leetCode_20;

import java.util.Stack;

/**

* @author dimdark

* @date 2017-10-07

* @time 3:21 PM

*/

public class Solution {

public boolean isValid(String s) {

if (s == null) return false;

Stack<Character> stk = new Stack<Character>();

boolean rst = true;

char[] cs = s.toCharArray();

for (int i = 0; i < cs.length; ++i) {

if (cs[i] == '(' || cs[i] == '[' || cs[i] == '{') {

stk.push(cs[i]);

} else {

if (stk.empty()) {

rst = false; break;

}

char ch = stk.peek();

if ((cs[i] == ')' && ch != '(') || (cs[i] == ']' && ch != '[')

|| (cs[i] == '}' && ch != '{')) {

rst = false; break;

}

stk.pop();

}

}

if (!stk.empty()) {

rst = false;

}

return rst;

}

}