【鏈接】
給出幾條關係,判斷有幾個是矛盾的
i-x代表“i屬於x類”
並查集內同組所有元素代表的情況同時發生或者同時不發生
分類:
同類:合併x-A和y-A,x-B和y-B,x-C和y-C
捕食關係(x吃y):合併x-A和y-B,x-B和y-C,x-C和y-A
【代碼】
#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);
}