假设表达式中允许包含圆括号、方括号和大括号3中括号，编写一个算法判断表达式中括号是否正确配对。用c语言实现

这里提供一个C语言实现的算法来判断表达式中的括号是否正确配对：

#include <stdio.h>
#include <stdlib.h>

#define MAX_SIZE 100

typedef struct {
    char data[MAX_SIZE];
    int top;
} Stack;

void init(Stack *s) {
    s->top = -1;
}

int is_empty(Stack *s) {
    return s->top == -1;
}

int is_full(Stack *s) {
    return s->top == MAX_SIZE - 1;
}

void push(Stack *s, char c) {
    if (is_full(s)) {
        printf("Stack is full.\n");
        exit(1);
    }
    s->data[++s->top] = c;
}

char pop(Stack *s) {
    if (is_empty(s)) {
        printf("Stack is empty.\n");
        exit(1);
    }
    return s->data[s->top--];
}

int is_match(char left, char right) {
    if (left == '(' && right == ')') {
        return 1;
    } else if (left == '[' && right == ']') {
        return 1;
    } else if (left == '{' && right == '}') {
        return 1;
    } else {
        return 0;
    }
}

int is_balanced(char *exp) {
    Stack s;
    init(&s);
    int i = 0;
    while (exp[i] != '\0') {
        if (exp[i] == '(' || exp[i] == '[' || exp[i] == '{') {
            push(&s, exp[i]);
        } else if (exp[i] == ')' || exp[i] == ']' || exp[i] == '}') {
            if (is_empty(&s)) {
                return 0;
            }
            char left = pop(&s);
            if (!is_match(left, exp[i])) {
                return 0;
            }
        }
        i++;
    }
    return is_empty(&s);
}

int main() {
    char exp[MAX_SIZE];
    printf("Enter an expression: ");
    scanf("%s", exp);
    if (is_balanced(exp)) {
        printf("The expression is balanced.\n");
    } else {
        printf("The expression is not balanced.\n");
    }
    return 0;
}

该算法使用了一个栈来存储左括号，当遇到右括号时，弹出栈顶元素并判断是否匹配。如果匹配，则继续扫描；否则，表达式不匹配。最后，如果栈为空，则表达式匹配；否则，表达式不匹配。