Submission #398024

#	Time	Username	Problem	Language	Result	Execution time	Memory
398024		Charis02	Election Campaign (JOI15_election_campaign)	C++14	20 / 100	1090 ms	41668 KiB

election_campaign

/*

https://oj.uz/problem/view/JOI15_election_campaign

O(NM) Code

*/

#include<iostream>
#include<vector>
#include<string.h>
#define ll long long
#define pi pair < ll,ll >
#define mp(a,b) make_pair(a,b)
#define MAX_N 100004

using namespace std;

vector < int > graph[MAX_N];
vector < pair < pi,ll > > tours[MAX_N];
ll jump_memo[MAX_N][21];
ll tin[MAX_N],tout[MAX_N],cur_time;
ll dp[MAX_N],S[MAX_N];
int n,m;

int jump(int x,int i) // find 2^i -th ancestor of x
{
    if(jump_memo[x][i] != -1)
        return jump_memo[x][i];
    return jump_memo[x][i] = jump(jump(x,i-1),i-1);
}

bool is_ancestor(int x,int y) // returns if x is ancestor of y
{
    return (tin[x] <= tin[y] && tout[x] >= tout[y]);
}

int get_lca(int x,int y)
{
    if(is_ancestor(x,y))
        return x;
    if(is_ancestor(y,x))
        return y;

    for(int i = 20;i >= 0;i--)
    {
        if(!is_ancestor(jump(x,i),y))
            x = jump(x,i);
    }

    return jump(x,0);
}

void dfs(int cur,int par)
{
    tin[cur] = cur_time++;
    jump_memo[cur][0] = par;

    for(int i = 0;i < graph[cur].size();i++)
    {
        int v = graph[cur][i];
        if(v == par)
            continue;
        dfs(v,cur);
    }

    tout[cur] = cur_time++;
    return;
}

void initialize()
{
    memset(jump_memo,-1,sizeof jump_memo);
    memset(dp,-1,sizeof dp);
    dfs(1,1);

    return;
}

void input()
{
    int a,b,c;

    cin >> n;

    for(int i = 0;i < n-1;i++)
    {
        cin >> a >> b;
        graph[a].push_back(b);
        graph[b].push_back(a);
    }

    initialize();
    cin >> m;

    for(int i = 0;i < m;i++)
    {
        cin >> a >> b >> c;
        tours[get_lca(a,b)].push_back(mp(mp(a,b),c));
    }

    return;
}

ll go(int cur,int par,int target)
{
    if(cur == target)
        return S[cur];
    for(int i = 0;i < graph[cur].size();i++)
    {
        int v = graph[cur][i];
        if(is_ancestor(v,target) && is_ancestor(cur,v))
            return go(v,cur,target)+S[cur]-dp[v];
    }
}

ll calc(int cur,int par)
{
    if(dp[cur] != -1)
        return dp[cur];

    for(int i = 0;i < graph[cur].size();i++)
    {
        int v = graph[cur][i];
        if(v==par)
            continue;

        S[cur] += calc(v,cur);
    }

    dp[cur] = S[cur];

    for(int i = 0;i < tours[cur].size();i++)
    {
        int x = tours[cur][i].first.first;
        int y = tours[cur][i].first.second;
        int C = tours[cur][i].second;

//        cout << "testing route " << x << " -> " << y << ".  lca is " << cur << ". Gain is " << C << ". ";
//        cout << "to x: " << go(cur,par,x) << " to y: " << go(cur,par,y) << "  S: " << S[cur] << " " << go(cur,par,x)+go(cur,par,y) - S[cur] + C << endl;

        dp[cur] = max(dp[cur],go(cur,par,x)+go(cur,par,y) - S[cur] + C); // S[cur] is counted twice
    }

  //  cout << "here " << cur << " " << dp[cur] << endl;
    return dp[cur];
}

void solve()
{
    cout << calc(1,1) << endl;
}

int main()
{
    input();
    solve();

    return 0;
}

Compilation message (stderr)

election_campaign.cpp: In function 'void dfs(int, int)':
election_campaign.cpp:59:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   59 |     for(int i = 0;i < graph[cur].size();i++)
      |                   ~~^~~~~~~~~~~~~~~~~~~
election_campaign.cpp: In function 'long long int go(int, int, int)':
election_campaign.cpp:109:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  109 |     for(int i = 0;i < graph[cur].size();i++)
      |                   ~~^~~~~~~~~~~~~~~~~~~
election_campaign.cpp: In function 'long long int calc(int, int)':
election_campaign.cpp:122:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  122 |     for(int i = 0;i < graph[cur].size();i++)
      |                   ~~^~~~~~~~~~~~~~~~~~~
election_campaign.cpp:133:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<std::pair<long long int, long long int>, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  133 |     for(int i = 0;i < tours[cur].size();i++)
      |                   ~~^~~~~~~~~~~~~~~~~~~
election_campaign.cpp: In function 'long long int go(int, int, int)':
election_campaign.cpp:115:1: warning: control reaches end of non-void function [-Wreturn-type]
  115 | }
      | ^

• Subtask 1: 10 / 10
• Subtask 2: 0 / 5
• Subtask 3: 0 / 5
• Subtask 4: 0 / 30
• Subtask 5: 10 / 10
• Subtask 6: 0 / 40