color matrix sda

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#define LAST_COL 4
int n = 4, m = 4;
int matrix[111][111];

bool valid(int row, int col, int color) {
    if ((row > 0 && col > 0 && matrix[row - 1][col - 1] == color) ||
        (row > 0 && col < m - 1 && matrix[row - 1][col + 1] == color) ||
        (row < n - 1 && col > 0 && matrix[row + 1][col - 1] == color) ||
        (row < n - 1 && col < m - 1 && matrix[row + 1][col + 1] == color)) {
        return false;
    }
    return true;
}

void printMatrix() {
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            printf("%d ", matrix[i][j]);
        }
        puts("");
    }
}

void bktr(int i, int j) {
    if (i == n) {
        printMatrix();
        puts("----------------------------------");
        return;
    }
    for (int c = 1; c <= LAST_COL; c++) {
        if (valid(i, j, c)) {
            matrix[i][j] = c;
            int nxtJ = j == m ? 0 : j + 1;
            int nxtI = j == m ? i + 1 : i;
            bktr(nxtI, nxtJ);
        }
    }
}


int main(void) {
    bktr(0, 0);
    return 0;
}