POJ1182 食物鏈

用變形的查並集。

#include <iostream>
#include <vector>
#include <cstdio>
#include <algorithm>
#include <map>
#include <queue>
#include <string.h>
#include <stack>

using namespace std;
const int MAX_K = 100001;
const int MAX_N = 150001;
int par[MAX_N], height[MAX_N];
int T[MAX_K], X[MAX_K], Y[MAX_K];
int N, K;

void init(int n) {
    for (int i = 0; i < n; i++) {
        par[i] = i;
        height[i] = 0;
    }
}

int find(int x) {
    if (par[x] == x) {
        return x;
    } else
        return find(par[x]);
}

void unite(int x, int y) {
    x = find(x);
    y = find(y);
    if (x == y)
        return;
    if (height[x] < height[y])
        par[x] = y;
    else if (height[x] > height[y])
        par[y] = x;
    else {
        par[y] = x;
        height[x]++;
    }
}

bool same(int x, int y) {
    return find(x) == find(y);
}

void solve() {
    init(N * 3);
    int ans = 0;
//    x,x+N,x+2*N,代表x-A,x-B,x-C
    for (int i = 0; i < K; i++) {
        int t = T[i];
        int x = X[i] - 1, y = Y[i] - 1;

        if (x < 0 || x >= N || y < 0 || y >= N) {
            ans++;
            continue;
        }
        if (t == 1) {
            if (same(x, y + N) || same(x, y + 2 * N)) {
                ans++;
            } else {
                unite(x, y);
                unite(x + N, y + N);
                unite(x + 2 * N, y + 2 * N);
            }
        } else {
            if (same(x, y) || same(x, y + 2 * N)) {
                ans++;
            } else {
                unite(x, y + N);
                unite(x + N, y + 2 * N);
                unite(x + 2 * N, y);
            }
        }
    }
    cout << ans << endl;
}

int main() {
    scanf("%d %d", &N, &K);
    for (int i = 0; i < K; i++) {
        scanf("%d %d %d", &T[i], &X[i], &Y[i]);
    }
    solve();
    return 0;
}