Gym 101149I I - It's the Police

Posted 2020-08-17 stupid_one

http://codeforces.com/gym/101149/problem/I

考虑下面这个例子

4 3

1 2

1 3

1 4

应该是选 0 0 1 1这样是最优的，我们不选1号，因为如果选1号作为非法分子点，那么2、3、4也不能有警察了，这不行。

那么究竟选呢？

很明显的一个道理是，选出儿子数最小的那个点，作为非法分子点，那么不放警察的地方就变得小了。

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <algorithm>
#define ios ios::sync_with_stdio(false)
using namespace std;
#define inf (0x3f3f3f3f)
typedef long long int LL;

#include <iostream>
#include <sstream>
#include <vector>
#include <set>
#include <map>
#include <queue>
#include <string>
const int maxn = 2e5 + 20;
vector<int>son[maxn];
bool vis[maxn];
void work() {
    IOS;
    int n, m;
    cin >> n >> m;
    for (int i = 1; i <= m; ++i) {
        int u, v;
        cin >> u >> v;
        son[u].push_back(v);
        son[v].push_back(u);
    }
    int mi = inf;
    int id = inf;
    for (int i = 1; i <= n; ++i) {
        if (son[i].size() < mi) {
            mi = son[i].size();
            id = i;
        }
    }
    vis[id] = 1;
    for (int i = 0; i < son[id].size(); ++i) {
        vis[son[id][i]] = 1;
    }
    for (int i = 1; i <= n; ++i) {
        printf("%d ", !vis[i]);
    }
}
int main() {
#ifdef local
    freopen("data.txt","r",stdin);
#endif
    work();
    return 0;
}

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