Poj 2965 the pilots brothers 'refrigerator BFS + bitwise operation

The refrigerator has 16 switches, which are arranged in a 4*4 matrix. Each time you change the status of a switch, all the switches in the same column with it must also change the status. Find the minimum number of adjustments required to open the refrigerator.
Problem: the DFS should also work.

#include <queue>#include <iostream>using namespace std;queue<int> que;int step[1<<16];int point[1<<16];int cell[] = { 4383, 8751, 17487, 34959, 4593, 8946, 17652, 35064, 7953, 12066, 20292, 36744, 61713, 61986, 62532, 63624 };int main(){char ch; int i, pos = 0;for ( i = 0; i < 16; i++ ){cin >> ch;if ( ch == '+' )pos += ( 1 << i );}memset(step,-1,sizeof(step));memset(point,-1,sizeof(point));que.push ( pos );step[pos] = 0;int current, next;while ( !que.empty () ){current = que.front ();que.pop();for ( i = 0; i < 16; i++ ){next = current ^ cell[i];if ( step[next] == -1 ){point[next] = i;step[next] = step[current] + 1;que.push ( next );}if ( next == 0 ){cout << step[current] + 1 << endl;while ( next != pos ){cout << point[next] / 4 + 1 << ' ' << point[next] % 4 + 1 << endl;next = next ^ cell[point[next]];}return 0;}}}return 0;}