Maze solver using backtracking

/*
 * Simple maze solver
 * Author: Sergio Milardovich <[email protected]>
 * Based on http://www.youtube.com/watch?v=FJkT_dRjX94&list=PLTZbNwgO5ebpqWBmBx0lpy9IYFMSQcrL-
 * This script is only for academic usage
 */

#include <math.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>

bool isValid(int M[999][999], int i, int j);
bool solveMazeUtil(int M[999][999], int x, int y, int sol[999][999]);


void generateRandomMaze(int M[999][999], int sol[999][999]);
void printMaze(int maze[999][999]);
void solveMaze(int M[999][999], int sol[999][999]);

int m,n;
int M[999][999];
int sol[999][999];

void main(){
    srand(time(NULL));

    scanf("%d", &m);
    scanf("%d", &n);

    generateRandomMaze(M,sol);
    printMaze(M);

    printf("\n");
    solveMaze(M,sol);
    printf("\n");
}

bool isValid(int M[999][999], int i, int j){
    if((i >= 0 && i <= m) && (j >= 0 && j <= n) && M[i][j] == 1){
        return true;
    } else {
        return false;
    }
}

void solveMaze(int M[999][999], int sol[999][999]){
    if(solveMazeUtil(M,0,0,sol) == false){
        printf("No solution");
    } else {
        printMaze(sol);
    }
}

bool solveMazeUtil(int M[999][999], int x, int y, int sol[999][999]){
    if(x == m-1 && y == n-1){
        sol[x][y] = 1;
        return true;
    }
    if(isValid(M,x,y) == true){
        sol[x][y] = 1;

        if (solveMazeUtil(M, x+1, y, sol) == 1)
            return true;

        if (solveMazeUtil(M, x, y+1, sol) == 1)
            return true;

        sol[x][y] = 0;
        return false;
    }
    return false;
}

void generateRandomMaze(int M[999][999], int sol[999][999]){
    int i,j;
    for(i=0;i<m;i++){
        for(j=0;j<n;j++){
            M[i][j] = (rand()%2);
            sol[i][j] = 0;
        }
    }
}

void printMaze(int maze[999][999]){
    int i,j;
    for(i=0;i<m;i++){
        for(j=0;j<n;j++){
            printf("%d ",maze[i][j]);
        }
        printf("\n");
    }

}