多边形染色

Posted 2020-10-28 kcfzyhq

【代码】

#include<bits/stdc++.h>

using namespace std;

const int N = 51000, mod = 987654321;

int n, m, c, f[N][11], uncol[N][11], v[N];
int x, y, z, ans = 0;
int main() {
	memset(uncol, 0, sizeof uncol);
	memset(v, 0, sizeof v);
	scanf("%d%d%d", &n, &m, &c);
	for(int i = 1; i <= m; i++) {
		scanf("%d%d%d", &x, &y, &z);
		if(x == 1) {
			for(int j = 1; j <= c; j++)
				if(j != z)
					uncol[y][j] = true;
		}
		if(x == 2) uncol[y][z] = true;
		if(x == 3) {
			if(y < z) swap(y, z);
			v[y] = true;
		}
	}
	for(int p = 1; p <= c; p++) {
		if(uncol[1][p]) continue;
		memset(f, 0, sizeof f);
		f[1][p] = 1;
		for(int i = 2; i < n; i++)
			for(int j = 1; j <= c; j++) {
				if(uncol[i][j])continue;
				if(v[i]) {
					f[i][j] += f[i-1][j];
					f[i][j] %= mod;
				} else {
					for(int k = 1; k <= c; k++)
						if(j != k) {
							f[i][j] += f[i-1][k];
							f[i][j] %= mod;
						}
				}
			}
		for(int i = 1; i <= c; i++) {
			if(uncol[n][i] || i == p) continue;
			if(v[n]) {
				f[n][i] += f[n - 1][i];
				f[n][i] %= mod;
			} else {
				for(int k = 1; k <= c; k++)
					if(i != k) {
						f[n][i] += f[n - 1][k];
						f[n][i] %= mod;
					}
			}
			ans += f[n][i];
			ans %= mod;
		}
	}
	printf("%d\\n", ans);
	return 0;
}