Codeforces 581F Zublicanes and Mumocrates 树形dp

dp[ i ][ j ][ k ] 表示以 i 为根的子树，占领 i 的是 j 并且第一个人占了 i 子树的 k 个叶子节点的最小值。

然后随便d 1 d 就好了。

#include<bits/stdc++.h>

#define LL long long

#define LD long double

#define ull unsigned long long

#define fi first

#define se second

#define mk make_pair

#define PLL pair<LL, LL>

#define PLI pair<LL, int>

#define PII pair<int, int>

#define SZ(x) ((int)x.size())

#define ALL(x) (x).begin(), (x).end()

#define fio ios::sync_with_stdio(false); cin.tie(0);

using namespace std;

const int N =  + ;

const int inf = 0x3f3f3f3f;

const LL INF = 0x3f3f3f3f3f3f3f3f;

const int mod = 1e9 + ;

const double eps = 1e-;

const double PI = acos(-);

template<class T, class S> inline void add(T& a, S b) {a += b; if(a >= mod) a -= mod;}

template<class T, class S> inline void sub(T& a, S b) {a -= b; if(a < ) a += mod;}

template<class T, class S> inline bool chkmax(T& a, S b) {return a < b ? a = b, true : false;}

template<class T, class S> inline bool chkmin(T& a, S b) {return a > b ? a = b, true : false;}

int n, leaf;

int dp[N][][N];

int tmp[][N];

int sum[N];

bool isleaf[N];

vector<int> G[N];

void dfs(int u, int fa) {

    if(isleaf[u]) {

        dp[u][][] = dp[u][][] = ;

        sum[u] = ;

        return;

    }

    dp[u][][] = dp[u][][] = ;

    for(auto& v : G[u]) {

        if(v == fa) continue;

        dfs(v, u);

        memset(tmp, inf, sizeof(tmp));

        for(int i = ; i < ; i++) {

            for(int j = ; j < ; j++) {

                for(int c1 = ; c1 <= sum[u]; c1++) {

                    for(int c2 = ; c2 <= sum[v]; c2++) {

                        chkmin(tmp[i][c1 + c2], dp[u][i][c1] + dp[v][j][c2] + (i != j));

                    }

                }

            }

        }

        sum[u] += sum[v];

        memcpy(dp[u], tmp, sizeof(dp[u]));

    }

}

int main() {

    memset(dp, inf, sizeof(dp));

    scanf("%d", &n);

    for(int i = ; i < n; i++) {

        int u, v;

        scanf("%d%d", &u, &v);

        G[u].push_back(v);

        G[v].push_back(u);

    }

    if(n == ) return puts(""), ;

    int root = -;

    for(int i = ; i <= n; i++) {

        if(SZ(G[i]) != ) root = i;

        else leaf++, isleaf[i] = true;

    }

    dfs(root, );

    printf("%d\n", min(dp[root][][leaf >> ], dp[root][][leaf >> ]));

    return ;

}

/*

*/

秒客网

Codeforces 581F Zublicanes and Mumocrates 树形dp

相关文章