Given a string containing just the characters ‘(‘, ‘)‘, ‘{‘, ‘}‘, ‘[‘ and ‘]‘, determine if the input string is valid.
The brackets must close in the correct order, "()" and "()[]{}" are all valid but "(]" and "([)]" are not.
将左括号压入数组，然后遇到右括号时就与数组中的最后一个元素比较，匹配则继续下一个元素，不匹配输出false，直到所有的元素都执行一遍，期间如果遇到右括号时数组为空，则输出false，最后看数组的元素是否为0，是则输出true，否则输出false。
bool isValid(char *s) { char c[100]; int index = 0; for(int i = 0; i<strlen(s); i++){ if(s[i] == ‘(‘ || s[i] == ‘[‘ || s[i] == ‘{‘) c[index++] = s[i]; if(s[i] == ‘)‘ || s[i] == ‘]‘ || s[i] == ‘}‘){ if(index == 0) return false; char r = c[index-1]; switch(s[i]){ case ‘)‘: if(r == ‘(‘) index--; else return false; break; case ‘]‘: if(r == ‘[‘) index--; else return false; break; case ‘}‘: if(r == ‘{‘) index--; else return false; break; } } } if(index == 0){ return true; } else{ return false; } }
原文：http://www.cnblogs.com/zhhc/p/4363798.html