3 ms·
while grid[index] == 9 || grid[index] != 0 { is equivalent to while grid[index] != 0 { so when you backtrack, you always backtrack all the way to the begin
by yorwba 2y ago
while grid[index] == 9 || grid[index] != 0 {
is equivalent to
while grid[index] != 0 {
so when you backtrack, you always backtrack all the way to the beginning.
I think you want
while grid[index] == 9 || initial_grid[index] != 0 {
grid[index] = initial_grid[index];
or something to that effect.