HDU 2813 One fihgt one

题目链接

题意：吕布n个武将，曹操m个，问吕布每个武将参加一场战斗，不能跟同一个武将打，问最小受到伤害

思路：显然的KM最大匹配

代码：

#include <cstdio>
#include <cstring>
#include <cmath>
#include <map>
#include <string>
#include <algorithm>
using namespace std;

const int MAXNODE = 505;

typedef int Type;
const Type INF = 0x3f3f3f3f;

struct KM {
	int n, m;
	Type g[MAXNODE][MAXNODE];
	Type Lx[MAXNODE], Ly[MAXNODE], slack[MAXNODE];
	int left[MAXNODE], right[MAXNODE];
	bool S[MAXNODE], T[MAXNODE];

	void init(int n, int m) {
		this->n = n;
		this->m = m;
		for (int i = 0; i < n; i++)
			for (int j = 0; j < m; j++)
				g[i][j] = -INF;
	}

	void add_Edge(int u, int v, Type val) {
		g[u][v] = val;
	}

	bool dfs(int i) {
		S[i] = true;
		for (int j = 0; j < m; j++) {
			if (T[j]) continue;
			Type tmp = Lx[i] + Ly[j] - g[i][j];
			if (!tmp) {
				T[j] = true;
				if (left[j] == -1 || dfs(left[j])) {
					left[j] = i;
					right[i] = j;
					return true;
				}
			} else slack[j] = min(slack[j], tmp);
		}
		return false;
	}

	void update() {
		Type a = INF;
		for (int i = 0; i < m; i++)
			if (!T[i]) a = min(a, slack[i]);
		for (int i = 0; i < n; i++)
			if (S[i]) Lx[i] -= a;
		for (int i = 0; i < m; i++)
			if (T[i]) Ly[i] += a;
	}

	Type km() {
		memset(left, -1, sizeof(left));
		memset(right, -1, sizeof(right));
		memset(Ly, 0, sizeof(Ly));
		for (int i = 0; i < n; i++) {
			Lx[i] = -INF;
			for (int j = 0; j < m; j++)
				Lx[i] = max(Lx[i], g[i][j]);
		}
		for (int i = 0; i < n; i++) {
			for (int j = 0; j < m; j++) slack[j] = INF;
			while (1) {
				memset(S, false, sizeof(S));
				memset(T, false, sizeof(T));
				if (dfs(i)) break;
				else update();
			}
		}
		Type ans = 0;
		for (int i = 0; i < n; i++)
			ans += g[i][right[i]];
		return -ans;
	}
} gao;

int n, m, k;
map<string, int> hash[2];
int hn[2], w;
char a[25], b[25];

int get(char *str, int now) {
	if (!hash[now].count(str)) hash[now][str] = hn[now]++;
	return hash[now][str];
}

int main() {
	while (~scanf("%d%d%d", &n, &m, &k)) {
		gao.init(n, m);
		hn[0] = hn[1] = 0;
		hash[0].clear(); hash[1].clear();
		while (k--) {
			scanf("%s%s%d", a, b, &w);
			int u = get(a, 0);
			int v = get(b, 1);
			gao.add_Edge(u, v, -w);
		}
		printf("%d\n", gao.km());
	}
	return 0;
}