[AcWing 1250] 格子游戏

#include<bits/stdc++.h>

using namespace std;

typedef long long LL;

const int N = 1e5 + 10;

int n, m;
int p[N];

int find(int x)
{
    if (p[x] != x)
        p[x] = find(p[x]);
    return p[x];
}

void solve()
{
    cin >> n >> m;
    for (int i = 1; i <= n * n; i ++)
        p[i] = i;
    int res = 0;
    for (int i = 1; i <= m; i ++) {
        int x, y;
        char c;
        cin >> x >> y >> c;
        if (res)
            continue;
        int a = (x - 1) * n + y;
        int b = 0;
        if (c == 'D')
            b = a + n;
        else
            b = a + 1;
        if (find(a) == find(b))
            res = i;
        p[find(a)] = find(b);
    }
    if (!res)
        cout << "draw" << endl;
    else
        cout << res << endl;
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);

    solve();

    return 0;
}