Submission #163146

#	Time	Username	Problem	Language	Result	Execution time	Memory
163146		arnold518	Chase (CEOI17_chase)	C++14	100 / 100	2945 ms	347088 KiB

chase

#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

const int MAXN = 1e5;
const int MAXK = 100;

int N, K;
ll P[MAXN+10], S[MAXN+10], dp1[MAXN+10][MAXK+10], dp2[MAXN+10][MAXK+10], ans;
vector<int> adj[MAXN+10];

void dfs1(int now, int bef)
{
    int i, j;
    for(int nxt : adj[now])
    {
        if(nxt==bef) continue;
        dfs1(nxt, now);
    }
    for(int nxt : adj[now]) S[now]+=P[nxt];

    for(i=1; i<=K; i++)
    {
        ll val=0;
        for(int nxt : adj[now])
        {
            if(nxt==bef) continue;
            val=max(val, dp1[nxt][i-1]);
            dp1[now][i]=max(dp1[now][i], dp1[nxt][i]);
        }
        dp1[now][i]=max(dp1[now][i], S[now]-P[bef]+val);
    }
}

vector<pll> V[MAXK+10];
void dfs2(int now, int bef)
{
    int i, j;

    for(i=0; i<=K; i++) V[i].clear();
    for(int nxt : adj[now])
    {
        if(nxt==bef) continue;
        for(i=0; i<=K; i++) V[i].push_back({dp1[nxt][i], nxt});
    }
    for(i=0; i<=K; i++) V[i].push_back({dp2[now][i], now});
    for(i=0; i<=K; i++) sort(V[i].begin(), V[i].end(), greater<pll>());

    for(int nxt : adj[now])
    {
        if(nxt==bef) continue;
        for(i=1; i<=K; i++)
        {
            for(j=0; j<V[i].size(); j++)
            {
                if(V[i][j].second==nxt) continue;
                dp2[nxt][i]=max(dp2[nxt][i], V[i][j].first);
                break;
            }
            for(j=0; j<V[i-1].size(); j++)
            {
                if(V[i-1][j].second==nxt) continue;
                dp2[nxt][i]=max(dp2[nxt][i], V[i-1][j].first+S[now]-P[nxt]);
                break;
            }
        }
    }

    for(int nxt : adj[now])
    {
        if(nxt==bef) continue;
        dfs2(nxt, now);
    }
}

void dfs3(int now, int bef)
{
    for(int nxt : adj[now])
    {
        if(nxt==bef) continue;
        dfs3(nxt, now);
    }

    if(bef==0)
    {
        ans=max(ans, dp1[now][K]);
    }
    else
    {
        ll val=0;
        for(int nxt : adj[now])
        {
            if(nxt==bef) continue;
            val=max(val, dp1[nxt][K]);
        }
        val=max(val, dp2[now][K]); ans=max(ans, val);

        val=0;
        for(int nxt : adj[now])
        {
            if(nxt==bef) continue;
            val=max(val, dp1[nxt][K-1]);
        }
        val=max(val, dp2[now][K-1]);
        val+=S[now];
        ans=max(ans, val);
    }
}

int main()
{
    int i, j, k;

    scanf("%d%d", &N, &K);
    for(i=1; i<=N; i++) scanf("%lld", &P[i]);
    for(i=1; i<N; i++)
    {
        int u, v;
        scanf("%d%d", &u, &v);
        adj[u].push_back(v);
        adj[v].push_back(u);
    }

    if(K==0) return !printf("0");

    for(i=0; i<=K; i++) dp2[1][i]=-1e17;

    dfs1(1, 0);
    dfs2(1, 0);
    dfs3(1, 0);
    printf("%lld", ans);
}

Compilation message (stderr)

chase.cpp: In function 'void dfs1(int, int)':
chase.cpp:17:12: warning: unused variable 'j' [-Wunused-variable]
     int i, j;
            ^
chase.cpp: In function 'void dfs2(int, int)':
chase.cpp:57:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             for(j=0; j<V[i].size(); j++)
                      ~^~~~~~~~~~~~
chase.cpp:63:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             for(j=0; j<V[i-1].size(); j++)
                      ~^~~~~~~~~~~~~~
chase.cpp: In function 'int main()':
chase.cpp:115:12: warning: unused variable 'j' [-Wunused-variable]
     int i, j, k;
            ^
chase.cpp:115:15: warning: unused variable 'k' [-Wunused-variable]
     int i, j, k;
               ^
chase.cpp:117:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d%d", &N, &K);
     ~~~~~^~~~~~~~~~~~~~~~
chase.cpp:118:30: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     for(i=1; i<=N; i++) scanf("%lld", &P[i]);
                         ~~~~~^~~~~~~~~~~~~~~
chase.cpp:122:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d", &u, &v);
         ~~~~~^~~~~~~~~~~~~~~~

• Subtask 1: 20 / 20
• Subtask 2: 20 / 20
• Subtask 3: 30 / 30
• Subtask 4: 30 / 30