PKU 2771 - Guardian of Decency (最大独立集)
题意
问符合条件的最大人数
思路
反一下。求能谈恋爱的最大匹配,用n - 最大匹配即可。
代码
#include <cstdio>
#include <stack>
#include <set>
#include <iostream>
#include <string>
#include <vector>
#include <queue>
#include <functional>
#include <cstring>
#include <algorithm>
#include <cctype>
#include <string>
#include <map>
#include <cmath>
#define LL long long
#define SZ(x) (int)x.size()
#define Lowbit(x) ((x) & (-x))
#define MP(a, b) make_pair(a, b)
#define MS(arr, num) memset(arr, num, sizeof(arr))
#define PB push_back
#define F first
#define S second
#define ROP freopen("input.txt", "r", stdin);
#define MID(a, b) (a + ((b - a) >> 1))
#define LC rt << 1, l, mid
#define RC rt << 1|1, mid + 1, r
#define LRT rt << 1
#define RRT rt << 1|1
#define BitCount(x) __builtin_popcount(x)
const double PI = acos(-1.0);
const int INF = 0x3f3f3f3f;
using namespace std;
const int MAXN = 1100+ 10;
const int MOD = 1e9 + 7;
const int dir[][2] = { {-1, 0}, {1, 0}, {0, -1}, {0, 1} };
typedef pair<int, int> pii;
typedef vector<int>::iterator viti;
typedef vector<pii>::iterator vitii;
struct PEO
{
int age;
string sex, hb, mus;
}peo[MAXN];
struct EDGE
{
int from, to;
};
struct BIMATCHING
{
int link[MAXN], head[MAXN], next[MAXN * MAXN];
bool vis[MAXN];
vector<EDGE> edges;
void init()
{
MS(link, -1); MS(head, -1);
edges.clear();
}
void add_edge(int from, int to)
{
edges.PB((EDGE){from, to});
int m = SZ(edges);
next[m - 1] = head[from];
head[from] = m - 1;
}
bool dfs(int u)
{
for (int i = head[u]; i != -1; i = next[i])
{
EDGE &e = edges[i];
int v = e.to;
if (!vis[v])
{
vis[v] = 1;
if (link[v] == -1 || dfs(link[v]))
{
link[v] = u;
return true;
}
}
}
return false;
}
int hungary(int n) //n是待匹配的总数,这里默认从1开始
{
int res = 0;
for (int i = 1; i <= n; i++)
{
MS(vis, 0);
if (dfs(i)) res++;
}
return res;
}
}hun;
bool Check(int i, int j)
{
if (abs(peo[i].age - peo[j].age) > 40 || peo[i].sex == peo[j].sex
|| peo[i].hb == peo[j].hb || peo[i].mus != peo[j].mus) return false;
return true;
}
int main()
{
ios::sync_with_stdio(0);
//ROP;
int T, i, j;
cin >> T;
while (T--)
{
hun.init();
int n;
cin >> n;
for (i = 1; i <= n; i++)
{
cin >> peo[i].age >> peo[i].sex >> peo[i].mus >> peo[i].hb;
for (j = 1; j < i; j++)
if (Check(i, j))
{
hun.add_edge(j, i);
hun.add_edge(i, j);
}
}
cout << n - hun.hungary(n) / 2 << endl;
}
return 0;
}