Niitty

#define print_board for (int i = 0; i < n; i++) { std::cout << board[i] << '\n'; } std::cout << std::endl
#define print_flowers(flowers) for (int i = 0; i < 26; i++) { std::cout << ((flowers & (1<<i)) >> i); } std::cout << '\n' << "abcdefghijklmnopqrstuvwxyz" << std::endl
#define print_rect(r) std::cout << r.left << ' ' << r.right << ' ' << r.top << ' ' << r.bottom << std::endl
#define to_bit(c) (1<<(c - 'a'))
#define MAX_RECT ((rect) { .left = 0, .right = (int16_t) (n-1), .top = 0, .bottom = (int16_t) (n-1) })
#define rect_size(r) ((1 + r.right - r.left) * (1 + r.bottom - r.top))
#define bitmap uint32_t

#include <iostream>
#include <stdlib.h>
#include <stdint.h>

// note: int16_t only needed for last part!
// other parts can do with int8_t
typedef struct {
    int16_t left;
    int16_t right;
    int16_t top;
    int16_t bottom;
} rect;

bool valid_rect(char **board, uint16_t n, bitmap flowers, rect rectangle) {
    bitmap flowers_in_rect = 0;
    for (uint16_t x = rectangle.left; x <= rectangle.right; x++) {
        for (uint16_t y = rectangle.top; y <= rectangle.bottom; y++) {
            flowers_in_rect = flowers_in_rect | to_bit(board[x][y]);
            if (flowers == flowers_in_rect) { return true; }
        }
    }
    return false;
}

int main() {
    uint16_t n;
    bitmap found_flowers = 0;
    std::cin >> n;

    char **board = (char**) malloc((n) * sizeof(char*));
    
    for (unsigned int i = 0; i < n; i++) {
        char *row = (char*) malloc((n+1) * sizeof(char));
        std::cin >> row;
        for (unsigned int j = 0; j < n; j++) {
            found_flowers = found_flowers | to_bit(row[j]);
        }
        board[i] = row;
    }

    //print_flowers(found_flowers);
    unsigned int solutions = 0;
    
    rect smallest_rect = MAX_RECT;

    // naive solution to get a smallest rect solution
    while (smallest_rect.left <= smallest_rect.right && valid_rect(board, n, found_flowers, smallest_rect)) { smallest_rect.left++; }
    smallest_rect.left--;
    while (smallest_rect.left <= smallest_rect.right && valid_rect(board, n, found_flowers, smallest_rect)) { smallest_rect.right--; }
    smallest_rect.right++;
    while (smallest_rect.top <= smallest_rect.bottom && valid_rect(board, n, found_flowers, smallest_rect)) { smallest_rect.top++; }
    smallest_rect.top--;
    while (smallest_rect.top <= smallest_rect.bottom && valid_rect(board, n, found_flowers, smallest_rect)) { smallest_rect.bottom--; }
    smallest_rect.bottom++;

    // solutions enclosing the smallest rect need not be brute forced
    solutions += (smallest_rect.left + 1) * (n - smallest_rect.right) * (smallest_rect.top + 1) * (n - smallest_rect.bottom) - 1;
    
    // brute force everything smaller than that
    for (int16_t left = smallest_rect.left; left <= smallest_rect.right; left++) {
        for (int16_t right = left; right <= smallest_rect.right; right++) {
            for (int16_t top = smallest_rect.top; top <= smallest_rect.bottom; top++) {
                for (int16_t bottom = top; bottom <= smallest_rect.bottom; bottom++) {
                    if (valid_rect(board, n, found_flowers, (rect) {.left=left, .right=right, .top=top, .bottom=bottom})) {
                        solutions++;
                    }
                }
            }
        }
    } // */

    std::cout << solutions << std::endl;

    /*
    for (unsigned int i = 0; i < n; i++) {
        free(board[i]);
    }
    free(board);
    */

    return 0;
}

Test 1

Group: 1, 2, 3, 4, 5, 6

Verdict: WRONG ANSWER

Test 2

Group: 1, 2, 3, 4, 5, 6

Verdict: WRONG ANSWER

Test 3

Group: 1, 2, 3, 4, 5, 6

Verdict: WRONG ANSWER

Test 4

Group: 1, 2, 3, 4, 5, 6

Verdict: ACCEPTED

Test 5

Group: 1, 2, 3, 4, 5, 6

Verdict: ACCEPTED

Test 6

Group: 2, 3, 4, 5, 6

Verdict: WRONG ANSWER

Test 7

Group: 2, 3, 4, 5, 6

Verdict: WRONG ANSWER

Test 8

Group: 2, 3, 4, 5, 6

Verdict: WRONG ANSWER

Test 9

Group: 2, 3, 4, 5, 6

Verdict: WRONG ANSWER

Test 10

Group: 3, 4, 5, 6

Verdict: WRONG ANSWER

Test 11

Group: 3, 4, 5, 6

Verdict: WRONG ANSWER

Test 12

Group: 3, 4, 5, 6

Verdict: WRONG ANSWER

Test 13

Group: 3, 4, 5, 6

Verdict: WRONG ANSWER

Test 14

Group: 4, 5, 6

Verdict: WRONG ANSWER

Test 15

Group: 4, 5, 6

Verdict: WRONG ANSWER

Test 16

Group: 4, 5, 6

Verdict: WRONG ANSWER

Test 17

Group: 4, 5, 6

Verdict: TIME LIMIT EXCEEDED

Test 18

Group: 5, 6

Verdict: WRONG ANSWER

Test 19

Group: 5, 6

Verdict: WRONG ANSWER

Test 20

Group: 5, 6

Verdict: WRONG ANSWER

Test 21

Group: 5, 6

Verdict: TIME LIMIT EXCEEDED

Test 22

Group: 6

Verdict: WRONG ANSWER

Test 23

Group: 6

Verdict: WRONG ANSWER

Test 24

Group: 6

Verdict: WRONG ANSWER

Test 25

Group: 6

Verdict: TIME LIMIT EXCEEDED