HDU 4313 matrix tree DP

Question:

Tree with N points and m black spots

The following n-1 lines show the cost of the edge and delete the edge.

The following m black spots are marked as [0, n-1]

Delete some edges so that any two black spots are not connected.

The minimum cost for deletion.

Ideas:

Tree DP

Each vertex has two states: black or white.

If the dot itself is a black spot, there is only a black spot.

Otherwise, it can be considered that a black dot in the subtree is transferred up.

Therefore, DP [I] [0] is the status where I points are black spots.

#pragma comment(linker, "/STACK:1024000000,1024000000")#include <stdio.h>#include <algorithm>#include <iostream>#include <queue>using namespace std;typedef long long ll;const ll inf = 1e13;#define N 100100struct Edge{    int to; ll dis; int nex;    void put(){printf(" (%d,%lld)\n", to, dis);}}edge[N*2];int head[N], edgenum;void init(){memset(head, -1, sizeof head); edgenum = 0 ;}void add(int u, int v, ll d){    Edge E = {v, d, head[u]};    edge[edgenum] = E;    head[u] = edgenum++;}typedef long long ll;template <class T>inline bool rd(T &ret) {    char c; int sgn;    if(c=getchar(),c==EOF) return 0;    while(c!='-'&&(c<'0'||c>'9')) c=getchar();    sgn=(c=='-')?-1:1;    ret=(c=='-')?0:(c-'0');    while(c=getchar(),c>='0'&&c<='9') ret=ret*10+(c-'0');    ret*=sgn;    return 1;}template <class T>inline void pt(T x) {    if (x <0) {        putchar('-');        x = -x;    }    if(x>9) pt(x/10);    putchar(x%10+'0');}int n, black_num;bool black[N];ll dp[N][2];void dfs(int u, int fa){    ll tmp = 0;    for(int i = head[u]; ~i; i = edge[i].nex){        int v = edge[i].to; if(v == fa)continue;        dfs(v, u);        tmp += min(dp[v][0] + edge[i].dis, dp[v][1]);    }    dp[u][0] = dp[u][1] = inf;    if(black[u]){        dp[u][0] = tmp;    }    else {        dp[u][1] = tmp;        for(int i = head[u]; ~i; i = edge[i].nex){            int v = edge[i].to; if(v == fa)continue;            dp[u][0] = min(dp[u][0], dp[v][0] + tmp - min(dp[v][0] + edge[i].dis, dp[v][1]));        }    }}ll solve(){    dfs(0, 0);    if(black[0])        return dp[0][0];    else        return min(dp[0][0], dp[0][1]);}void input(){    init();    rd(n); rd(black_num);    ll d;    for(int i = 1, u, v; i < n; i++)    {        rd(u); rd(v); rd(d);        add(u, v, d);        add(v, u, d);    }    memset(black, 0, sizeof black);    while(black_num--)    {        int u; rd(u);        black[u] = 1;    }}int main(){    int T; rd(T);    while(T--){        input();        pt(solve()); putchar('\n');    }    return 0;}/*9916 50 1 11 2 61 3 1002 4 32 5 14 12 14 6 15 8 18 13 38 15 45 7 114 7 13 9 19 10 19 11 11 3 4 13 159 50 1 10 2 22 6  61 3 31 4 41 5 54 7 21 8 4835672 20 1 10001 01 01 112 10 1 100005 20 1 51 2 32 3 43 4 50 45 30 1 51 2 32 3 43 4 50 4 25 40 1 51 2 32 3 43 4 50 4 2 35 50 1 51 2 32 3 43 4 50 1 2 3 411 60 1 100 2 90 3 80 4 71 5 42 6 53 7 13 10 23 9 34 8 65 6 7 9 8 10ans:107101000000371217*/

HDU 4313 matrix tree DP