Submission #25424

#	Time	Username	Problem	Language	Result	Execution time	Memory
25424		tlwpdus	Election Campaign (JOI15_election_campaign)	C++14	100 / 100	486 ms	42288 KiB

election_campaign

#include <bits/stdc++.h>

using namespace std;

typedef pair<int,int> pii;

struct plan {
    int a, b, c;
    plan(int a, int b, int c):a(a),b(b),c(c){}
};

int n, m;
vector<int> lis[100100];
vector<plan> pl[100100];
int sz[100100];
map<int,int> *E[100100];
int D[100100];
int bias[100100];
int sps[100100][20];
int dep[100100];

void idfs(int here, int p, int d) {
    int i;
    sps[here][0] = p;
    dep[here] = d;
    for (i=0;i<lis[here].size();i++) {
        int there = lis[here][i];
        if (there==p) continue;
        idfs(there,here,d+1);
    }
}

void init() {
    int i, j;
    for (j=1;j<20;j++) {
        for (i=0;i<n;i++) sps[i][j] = ((~sps[i][j-1])?sps[sps[i][j-1]][j-1]:-1);
    }
}

int lca(int u, int v) {
    if (dep[u]>dep[v]) swap(u,v);
    int td = dep[v]-dep[u];
    int i;
    for (i=0;i<20;i++) {
        if ((td>>i)&1) v = sps[v][i];
    }
    if (u==v) return u;
    for (i=19;i>=0;i--) {
        if (sps[u][i]==sps[v][i]) continue;
        u=sps[u][i];v=sps[v][i];
    }
    return sps[u][0];
}

void dfs(int here, int p) {
    int i, maxi = -1, t = -1, dsum = 0;
    sz[here] = 1;
    for (i=0;i<lis[here].size();i++) {
        int there = lis[here][i];
        if (there==p) continue;
        dfs(there,here);
        if (maxi<sz[there]) {
            maxi=sz[there];
            t=there;
        }
        dsum += D[there];
        sz[here]+=sz[there];
    }
    if (~t) {
        E[here] = E[t];
        bias[here] = bias[t]+dsum-D[t];
    }
    else {
        E[here] = new map<int,int>();
        E[here]->insert(pii(here,0));
    }
    for (i=0;i<lis[here].size();i++) {
        int there = lis[here][i];
        if (there==p||there==t) continue;
        map<int,int>::iterator it = E[there]->begin();
        while(it!=E[there]->end()) {
            E[here]->insert(pii((*it).first,(*it).second+bias[there]-bias[here]+dsum-D[there]));
            it++;
        }
        E[there]->clear();
    }
    E[here]->insert(pii(here,dsum-bias[here]));
    D[here] = dsum;
    for (i=0;i<pl[here].size();i++) {
        D[here] = max(D[here],pl[here][i].c+(*E[here])[pl[here][i].a]+bias[here]+(*E[here])[pl[here][i].b]+bias[here]-dsum);
    }
}

int main() {
    int i;

    scanf("%d",&n);
    for (i=0;i<n-1;i++) {
        int x, y;
        scanf("%d%d",&x,&y);
        x--;y--;
        lis[x].push_back(y);
        lis[y].push_back(x);
    }
    idfs(0,-1,0);
    init();
    scanf("%d",&m);
    for (i=0;i<m;i++) {
        int a, b, c;
        scanf("%d%d%d",&a,&b,&c);
        a--;b--;
        pl[lca(a,b)].push_back(plan(a,b,c));
    }
    dfs(0,-1);
    printf("%d\n",D[0]);

    return 0;
}

Compilation message (stderr)

election_campaign.cpp: In function 'void idfs(int, int, int)':
election_campaign.cpp:26:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (i=0;i<lis[here].size();i++) {
               ^
election_campaign.cpp: In function 'void dfs(int, int)':
election_campaign.cpp:58:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (i=0;i<lis[here].size();i++) {
               ^
election_campaign.cpp:77:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (i=0;i<lis[here].size();i++) {
               ^
election_campaign.cpp:89:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (i=0;i<pl[here].size();i++) {
               ^
election_campaign.cpp: In function 'int main()':
election_campaign.cpp:97:19: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d",&n);
                   ^
election_campaign.cpp:100:28: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d",&x,&y);
                            ^
election_campaign.cpp:107:19: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d",&m);
                   ^
election_campaign.cpp:110:33: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%d%d",&a,&b,&c);
                                 ^

• Subtask 1: 10 / 10
• Subtask 2: 5 / 5
• Subtask 3: 5 / 5
• Subtask 4: 30 / 30
• Subtask 5: 10 / 10
• Subtask 6: 40 / 40