solve.c

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
bool isLeft(char c)
{
	return c == '(' || c == '[' || c == '{';
}
bool isMatch(char a, char b)
{
	return (a == '(' && b == ')')
		|| (a == '[' && b == ']')
		|| (a == '{' && b == '}');
}
bool isValid(char *s)
{
	int len = strlen(s);
	char *stack = malloc(sizeof(char) * len);
	int pos = -1;
	for (int i = 0; i < len; ++i) {
		if (isLeft(s[i])) {
			stack[++pos] = s[i];
		} else {
			if (isMatch(stack[pos], s[i])) {
				--pos;
			} else {
				return false;
			}
		}
	}
	free(stack);
	return pos == -1;
}
int main(int argc, char **argv)
{
	char s[20];
	printf("%d\n", isValid(""));
	while (scanf("%s", s) != EOF)
		printf("%d\n", isValid(s));
	return true;
}