【链接】
给出几条关系，判断有几个是矛盾的
i-x代表“i属于x类”
并查集内同组所有元素代表的情况同时发生或者同时不发生
分类：
同类：合并x-A和y-A,x-B和y-B,x-C和y-C
捕食关系(x吃y)：合并x-A和y-B,x-B和y-C,x-C和y-A
【代码】
#include<cstdio>
using namespace std;
const int maxn = 150010;
int fa[maxn];int find(int x) {return x == fa[x] ? x : fa[x]=find(fa[x]);
}void mix(int x, int y) {int fx = find(x);int fy = find(y);if (fx != fy)fa[fx] = fy;
}int main() {int n, k;scanf("%d%d", &n, &k);for (int i = 1; i <3* n; i++) {fa[i] = i;}int ans = 0;while (k--) {int d, x, y;scanf("%d%d%d", &d, &x, &y);if (x<=0 || y<=0 || x > n || y > n) {ans++;continue;}if (d == 1) {if (find(x) == find(y+n)||find(x)==find(y+2*n)) {ans++;}else {mix(x, y);mix(x + n, y + n);mix(x + 2 * n, y + 2 * n);}}else {if (find(x)==find(y+2*n)||find(x)==find(y)) {ans++;}else {mix(x, y + n);mix(x + n, y + 2 * n);mix(x + 2 * n, y);}}}printf("%d\n", ans);
}