UVa 639 Don't Get Rooked

/*coder: ACboydate: 2010-3-19result: 1Adescription: UVa 639 Don't Get Rooked*/#include <iostream>using namespace std;char chess[4][4];char tempChess[4][4];int everyPos[70000][16];int c;// 保存每个子集void print_subset(int n, int s){for (int i = 0; i < n; i++) {if (s & (1 << i)) everyPos[c][i] = 1;else everyPos[c][i] = 0;}c++;}// 生成所有的子集void findAllPos(int n) {for (int i = 0; i < 1 << n; i++) {print_subset(n, i);}}// 检查某一个位置上是否可以放车int checkRowColumn(int row, int column, int n) {int i;int ok = 1;for (i = column - 1; i >= 0 && tempChess[row][i] != 'X'; i--) {if (tempChess[row][i] == '*') {ok = 0;break;}}if (ok == 0) return 0;for (i = column + 1; i < n && tempChess[row][i] != 'X'; i++) {if (tempChess[row][i] == '*') {ok = 0;break;}}if (ok == 0) return 0;for (i = row - 1; i >= 0 && tempChess[i][column] != 'X'; i--) {if (tempChess[i][column] == '*') {ok = 0;break;}}if (ok == 0) return 0;for (i = row + 1; i < n && tempChess[i][column] != 'X'; i++) {if (tempChess[i][column] == '*') {ok = 0;break;}}if (ok == 0) return 0;return 1;}int checkLegal(int k, int n) {int count = 0;int i;int row;int column;// 对每种可能先把所有的车放到棋盘上，并记录车的个数countfor (i = 0; i < n * n; i++) {row = i / n;column = i % n;if (everyPos[k][i] == 1 && tempChess[row][column] == '.') {count++;tempChess[row][column] = '*';}}// 检查每个车的位置是否合法，如果每个车的位置都合法，则得到一个解int ok = 1;for (i = 0; i < n * n; ++i) {row = i / n;column = i % n;if (tempChess[row][column] == '*' && checkRowColumn(row, column, n) == 0) {ok = 0;break;}}// 如果所有车的位置都合法则返回车的个数if (ok) {return count;} else {return 0;}}int main(){int n;#ifndef ONLINE_JUDGEfreopen("639.txt", "r", stdin);#endifwhile (cin >> n) {if (n == 0) break;int i, j;for (i = 0; i < n; i++) {for (j = 0; j < n; j++) {cin >> chess[i][j];}}c = 0;findAllPos(n * n);int max = -1;for (i = 0; i < c; i++) {memcpy(tempChess, chess, sizeof(chess));int temp = checkLegal(i, n);if (temp > max) max = temp;}cout << max << endl;}return 0;}