The program crashes.It says stack overflow.
Please help me make it right.
Code:#include<iostream> using namespace std; static int grid[9][9]; void input(); void output(); void init(); bool solve(); bool is_safe(int,int,int); bool unassigned(int&,int&); int main() { init(); if (solve()) output(); else cout << "No solution\n"; } void input() { int i, j; for (i = 0; i < 9; i++) { cout << "enter row " << i + 1 << " values:\n"; for (j = 0; j < 9; j++) { cin >> grid[i][j]; while (grid[i][j]<0 || grid[i][j]>9) { cout << "invalid value.enter again : "; cin >> grid[i][j]; } } } } void output() { int i, j; for (i = 0; i<9; i++) { cout << '\t'; if (i == 3 || i == 6) cout << "-----------\n\t"; for (j = 0; j<9; j++) { if (j == 3||j==6) cout << '|'; cout << grid[i][j]; } cout << endl; } } void init() { char ans; do { input(); output(); cout << "is it correct (y/n) ? "; cin >> ans; if (ans == 'y' || ans == 'Y')break; cout << "Please try again.\n"; } while (true); } bool solve() { int k; int row, col; if (!unassigned(row,col)) return true; for (k = 1; k <= 9; k++) { if(is_safe(row, col, k)) grid[row][col]=k; if (solve()) return true; grid[row][col] = 0; } return false; } bool is_safe(int a, int b,int k) { int x, y, i, j; for (i = a, j = 0; j < 9; j++) { if (grid[i][j] == k) return false; } for (j = b, i = 0; i < 9; i++) { if (grid[i][j] == k) return false; } if (a < 3 && b < 3) { for (x = 0; x < 3; x++) for (y = 0; y < 3; y++) { if (grid[x][y] == k) return false; } return true; } else if (a < 3 && b < 6) { for (x = 0; x < 3; x++) for (y = 3; y < 6; y++) { if (grid[x][y] == k) return false; } return true; } else if (a < 3 && b < 9) { for (x = 0; x < 3; x++) for (y = 6; y < 9; y++) { if (grid[x][y] == k) return false; } return true; } else if (a < 6 && b < 3) { for (x = 3; x < 6; x++) for (y = 0; y < 3; y++) { if (grid[x][y] == k) return false; } return true; } else if (a < 6 && b < 6) { for (x = 3; x < 6; x++) for (y = 3; y < 6; y++) { if (grid[x][y] == k) return false; } return true; } else if (a < 6 && b < 9) { for (x = 3; x < 6; x++) for (y = 6; y < 9; y++) { if (grid[x][y] == k) return false; } return true; } else if (a < 9 && b < 3) { for (x = 6; x < 9; x++) for (y = 0; y < 3; y++) { if (grid[x][y] == k) return false; } return true; } else if (a < 9 && b < 6) { for (x = 6; x < 9; x++) for (y = 3; y < 6; y++) { if (grid[x][y] == k) return false; } return true; } else if (a < 9 && b < 9) { for (x = 6; x < 9; x++) for (y = 6; y < 9; y++) { if (grid[x][y] == k) return false; } return true; } } bool unassigned(int & i,int & j) { for (i = 0; i<9; i++) for (j = 0; j<9; j++) if (grid[i][j]==0) { return true; } return false; }
