math puzzle for third graders solver

mathPuzzleForThirdGraders.c

/*
Code to find all the permutations that solve the math puzzle for third graders from the image.

You're supposed to fill the blanks with the numbers 1 through 9 using each digit once.

Usage:
- Compile: gcc -O3 mathPyzzleForThirdGraders.c -o mathPyzzleForThirdGraders.out
- Run: ./mathPyzzleForThirdGraders.out
*/

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

void initializeArray(float *array, int arrayLength) {
    int i;

    for(i = 0; i < arrayLength; i++) {
        array[i] = (float)i+1.0;
    }
}

void printArray(float *array, int arrayLength) {
    int i;

    for(i = 0; i < arrayLength; i++) {
        printf("%g", array[i]);
        
        if(i < arrayLenght -1) {
            printf(",");
        }
    }

    printf("\n");
}

void swap(float *array, int x, int y) {
    float tmp = array[x];
    array[x] = array[y];
    array[y] = tmp;
}


void solvePuzzle(float * array, int arrayLength) {
    float result = array[0] + ((13 * array[1]) / array[2]) + array[3] + (12 * array[4]) - array[5] - 11 + ((array[6] * array[7]) / array[8]) -10;

    if(result == 66) {
        printArray(array, arrayLength);
    }
}

void permute(float *array, int left, int right, int arrayLength) {
    int i;

  if(left == right) {
        solvePuzzle(array, arrayLength);
    }
    else {
        for (i = left; i <= right; i++) {
            swap(array, left, i);
            permute(array, left+1, right, arrayLength);
            swap(array, left, i); // Backtrack
        }
    }
}

void main() {
    float array[9];
    int arrayLength = (sizeof(array)/sizeof(int));

    initializeArray(array, arrayLength);
    permute(array, 0, arrayLength-1, arrayLength);
}

mathPuzzleForThirdGraders.jpg

solutions.txt

1,2,6,4,7,8,5,3,9
1,2,6,4,7,8,3,5,9
1,3,2,4,5,8,7,9,6
1,3,2,4,5,8,9,7,6
1,3,2,9,5,6,7,4,8
1,3,2,9,5,6,4,7,8
1,3,4,7,6,5,2,9,8
1,3,4,7,6,5,9,2,8
1,3,6,2,7,9,5,4,8
1,3,6,2,7,9,4,5,8
1,3,9,4,7,8,5,2,6
1,3,9,4,7,8,2,5,6
1,4,8,2,7,9,5,3,6
1,4,8,2,7,9,3,5,6
1,5,3,9,4,2,7,8,6
1,5,3,9,4,2,8,7,6
1,5,2,3,4,8,7,9,6
1,5,2,3,4,8,9,7,6
1,5,2,8,4,7,3,9,6
1,5,2,8,4,7,9,3,6
1,9,6,4,5,8,7,3,2
1,9,6,4,5,8,3,7,2
1,9,6,7,5,2,4,3,8
1,9,6,7,5,2,3,4,8
2,1,4,3,7,9,5,6,8
2,1,4,3,7,9,6,5,8
2,3,6,1,7,9,5,4,8
2,3,6,1,7,9,4,5,8
2,4,8,1,7,9,5,3,6
2,4,8,1,7,9,3,5,6
2,8,6,9,4,1,7,5,3
2,8,6,9,4,1,5,7,3
2,9,6,3,5,1,7,4,8
2,9,6,3,5,1,4,7,8
3,2,1,5,4,7,8,9,6
3,2,1,5,4,7,9,8,6
3,2,4,8,5,1,7,9,6
3,2,4,8,5,1,9,7,6
3,2,8,6,5,1,7,9,4
3,2,8,6,5,1,9,7,4
3,1,4,2,7,9,5,6,8
3,1,4,2,7,9,6,5,8
3,5,2,1,4,8,7,9,6
3,5,2,1,4,8,9,7,6
3,6,4,9,5,8,7,1,2
3,6,4,9,5,8,1,7,2
3,9,6,2,5,1,7,4,8
3,9,6,2,5,1,4,7,8
3,9,2,8,1,5,7,6,4
3,9,2,8,1,5,6,7,4
4,2,6,1,7,8,5,3,9
4,2,6,1,7,8,3,5,9
4,3,2,1,5,8,7,9,6
4,3,2,1,5,8,9,7,6
4,3,9,1,7,8,5,2,6
4,3,9,1,7,8,2,5,6
4,9,6,1,5,8,7,3,2
4,9,6,1,5,8,3,7,2
5,2,1,3,4,7,8,9,6
5,2,1,3,4,7,9,8,6
5,3,1,7,2,6,8,9,4
5,3,1,7,2,6,9,8,4
5,4,1,9,2,7,8,3,6
5,4,1,9,2,7,3,8,6
5,4,8,9,6,7,1,3,2
5,4,8,9,6,7,3,1,2
5,1,2,9,6,7,3,4,8
5,1,2,9,6,7,4,3,8
5,7,2,8,3,9,1,6,4
5,7,2,8,3,9,6,1,4
5,9,3,6,2,1,7,8,4
5,9,3,6,2,1,8,7,4
6,2,8,3,5,1,7,9,4
6,2,8,3,5,1,9,7,4
6,3,1,9,2,5,7,8,4
6,3,1,9,2,5,8,7,4
6,9,3,5,2,1,7,8,4
6,9,3,5,2,1,8,7,4
7,2,8,9,6,5,1,3,4
7,2,8,9,6,5,3,1,4
7,3,2,8,5,9,1,6,4
7,3,2,8,5,9,6,1,4
7,3,4,1,6,5,2,9,8
7,3,4,1,6,5,9,2,8
7,3,1,5,2,6,8,9,4
7,3,1,5,2,6,9,8,4
7,5,2,8,4,9,1,3,6
7,5,2,8,4,9,3,1,6
7,6,4,8,5,9,1,3,2
7,6,4,8,5,9,3,1,2
7,1,4,9,6,5,2,3,8
7,1,4,9,6,5,3,2,8
7,9,6,1,5,2,4,3,8
7,9,6,1,5,2,3,4,8
8,2,4,3,5,1,7,9,6
8,2,4,3,5,1,9,7,6
8,3,2,7,5,9,1,6,4
8,3,2,7,5,9,6,1,4
8,5,2,7,4,9,3,1,6
8,5,2,7,4,9,1,3,6
8,5,2,1,4,7,3,9,6
8,5,2,1,4,7,9,3,6
8,6,4,7,5,9,3,1,2
8,6,4,7,5,9,1,3,2
8,7,2,5,3,9,1,6,4
8,7,2,5,3,9,6,1,4
8,9,2,3,1,5,7,6,4
8,9,2,3,1,5,6,7,4
9,2,8,7,6,5,3,1,4
9,2,8,7,6,5,1,3,4
9,3,2,1,5,6,7,4,8
9,3,2,1,5,6,4,7,8
9,3,1,6,2,5,7,8,4
9,3,1,6,2,5,8,7,4
9,4,8,5,6,7,3,1,2
9,4,8,5,6,7,1,3,2
9,4,1,5,2,7,8,3,6
9,4,1,5,2,7,3,8,6
9,5,3,1,4,2,7,8,6
9,5,3,1,4,2,8,7,6
9,6,4,3,5,8,7,1,2
9,6,4,3,5,8,1,7,2
9,8,6,2,4,1,7,5,3
9,8,6,2,4,1,5,7,3
9,1,4,7,6,5,3,2,8
9,1,4,7,6,5,2,3,8
9,1,2,5,6,7,4,3,8
9,1,2,5,6,7,3,4,8