usaa24/a1/program.c

#include <stdio.h>
#include <string.h>

#define MAX_LEN 101

typedef struct {
    char bracket;
    int position;
} StackItem;

int is_opening(char ch) {
    return ch == '(' || ch == '{' || ch == '[' || ch == '<';
}

int is_closing(char ch) {
    return ch == ')' || ch == '}' || ch == ']' || ch == '>';
}

char matching_bracket(char ch) {
    switch (ch) {
        case ')': return '(';
        case '}': return '{';
        case ']': return '[';
        case '>': return '<';
        default: return 0;
    }
}

char expected_closing(char ch) {
    switch (ch) {
        case '(': return ')';
        case '{': return '}';
        case '[': return ']';
        case '<': return '>';
        default: return 0;
    }
}

void check_brackets(const char *line) {
    StackItem stack[MAX_LEN];
    int stack_top = -1;
    
    printf("Read: %s\n", line);

    for (int i = 0; line[i] != '\0'; i++) {
        char ch = line[i];

        if (is_opening(ch)) {
            if (stack_top < MAX_LEN - 1) {
                stack[++stack_top].bracket = ch;
                stack[stack_top].position = i;
            } else {
                printf("Error: Stack overflow\n");
                return;
            }
        } else if (is_closing(ch)) {
            if (stack_top == -1) {
                printf("Unexpected closing bracket %c in %d \n", ch, i);
                return;
            } else if (stack[stack_top].bracket == matching_bracket(ch)) {
                stack_top--;
            } else {
                printf("Crossed bracket %c in %d, expected %c \n", ch, i,
                       expected_closing(stack[stack_top].bracket));
                return;
            }
        }
    }

    if (stack_top >= 0) {
        printf("Missing closing brackets:");
        printf(" ");
	while (stack_top >= 0) {
            printf("%c", expected_closing(stack[stack_top].bracket));
            stack_top--;
        }
        printf("\n");
    } else {
        printf("All brackets OK\n");
    }
}

int main() {
    char line[MAX_LEN];
    if (fgets(line, sizeof(line), stdin)) {
        line[strcspn(line, "\n")] = '\0';
        check_brackets(line);
    }
    return 0;
}