POJ 1733 Parity game——并查集 + 离散化

#include <cstdio>
#include <algorithm>
using namespace std;
const int maxn = 1e4 + 10;
int T, N, M, par[maxn], val[maxn], a[maxn];
struct Date {
    char str[10];
    int x, y;
}date[maxn];
int Query(int x) {
    if (x != par[x]) {
        int temp = par[x];
        par[x] = Query(par[x]);
        val[x] = val[x] ^ val[temp];
    }
    return par[x];
}
int main() {
    while (~scanf("%d %d", &N, &M)) {
        int cnt = 0;
        for (int i = 1; i <= M; i++) {
            scanf("%d%d%s", &date[i].x, &date[i].y, date[i].str); date[i].x--;
            a[++cnt] = date[i].x; a[++cnt] = date[i].y;
        }
        sort(a + 1, a + 1 + cnt);
        cnt = unique(a + 1, a + 1 + cnt) - a;
        for (int i = 1; i <= cnt; i++) par[i] = i, val[i] = 0;
        int ans = 0;
        for (int i = 1; i <= M; i++) {
            int x = lower_bound(a + 1, a + 1 + cnt, date[i].x) - a;
            int y = lower_bound(a + 1, a + 1 + cnt, date[i].y) - a;
            int a = Query(x), b = Query(y);
            if (a == b) {
                if ((val[x] ^ val[y]) % 2 == 0 && date[i].str[0] == 'o') break;
                if ((val[x] ^ val[y]) % 2 == 1 && date[i].str[0] == 'e') break;
                ans++;
            }
            else {
                if (date[i].str[0] == 'o') {
                    par[a] = b;
                    val[a] = val[x] ^ val[y] ^ 1;
                }
                else {
                    par[a] = b;
                    val[a] = val[x] ^ val[y];
                }
                ans++;
            }
        }
        printf("%d\n", ans);
    }
}