UVa 00141 - The Spot Game (simulation, pattern check)

Link: https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=3&page=show_problem&problem=77
Sol:

#include <iostream>
	#include <set>
	using namespace std;
	int main() {
	int n;
	int x, y;
	char move;
	bool winner;
	int playerWin;
	int playerWinMove;
	while(true) {
	cin >> n;
	if (n == 0) break;
	string grid(n * n, '0');
	string grid90(n * n, '0');
	string grid180(n * n, '0');
	string grid270(n * n, '0');
	winner = false;
	set<string> movesSoFar;
	for (int i = 0; i < 2 * n; i++) {
	cin >> x >> y >> move;
	if (winner) continue;
	--x, --y;
	char m = (move == '+')? '1' : '0';
	grid[x * n + y] = m;
	if (movesSoFar.find(grid) != movesSoFar.end()) {
	winner = true;
	playerWin = 2 - (i % 2);
	playerWinMove = i + 1;
	continue;
	}
	grid90[y * n + (n - x - 1)] = m;
	grid180[(n - x - 1) * n + (n - y - 1)] = m;
	grid270[(n - y - 1) * n + x] = m;
	movesSoFar.insert(grid);
	movesSoFar.insert(grid90);
	movesSoFar.insert(grid180);
	movesSoFar.insert(grid270);
	}
	if (winner)
	cout << "Player " << playerWin << " wins on move " << playerWinMove << endl;
	else
	cout << "Draw" << endl;
	}
	}