Submission #591525

#	Time	Username	Problem	Language	Result	Execution time	Memory
591525		FatihSolak	Shortcut (IOI16_shortcut)	C++17	38 / 100	2086 ms	5876 KiB

shortcut

#include "shortcut.h"
#include <bits/stdc++.h>
#define N 200005
using namespace std;
vector<pair<int,int>> adj[N];
bool on_circle[N];
long long ret = 0;
long long dfs(int v,int par){
    long long maxi = 0;
    for(auto u:adj[v]){
        if(u.first == par || on_circle[u.first])continue;
        long long tmp = dfs(u.first,v) + u.second;
        ret = max(ret,maxi + tmp);
        maxi = max(maxi,tmp);
    }
    return maxi;
}
long long get_ans(vector<int> circle,vector<int> circle_edges){
    assert(circle.size() == circle_edges.size());
    for(auto u:circle){
        on_circle[u] = 1;
    }
    ret = 0;
    vector<long long> depths;
    for(auto u:circle){
        depths.push_back(dfs(u,-1));
    }
    long long circle_length = 0;
    for(auto u:circle_edges){
        circle_length += u;
    }
    vector<long long> d = {0};
    for(int i = 1;i<circle.size();i++){
        d.push_back(d[i-1] + circle_edges[i-1]);
    }
    deque<pair<int,long long>> s1;
    int sz = circle.size();
    vector<long long> sufval(sz+1,-1e18);
    for(int i = sz-1;i>=0;i--){
        sufval[i] = max(sufval[i+1],depths[i] - d[i] + circle_length);
    }
    int pt1 = -1;
    for(int i = 0;i<circle.size();i++){
        while(pt1 + 1 < circle.size() && (d[pt1+1] - d[i]) < circle_length - (d[pt1 + 1] - d[i])){
            pt1++;
            while(s1.size() && s1.back().second <= d[pt1] + depths[pt1]){
                s1.pop_back();
            }
            s1.push_back({pt1,d[pt1] + depths[pt1]});
        }
        if(s1.size() && s1.front().first == i)
            s1.pop_front();
        if(s1.size()){
            ret = max(ret,s1.front().second+depths[i] -d[i]);
        }
        ret = max(ret,sufval[pt1+1]+depths[i] +d[i]);
    }
    for(auto u:circle){
        on_circle[u] = 0;
    }
    return ret;
}
long long find_shortcut(int n, std::vector<int> l, std::vector<int> d, int nwedge)
{
    for(int i = 0;i<n-1;i++){
        adj[i].push_back({i+1,l[i]});
        adj[i+1].push_back({i,l[i]});
    }
    for(int i = 0;i<n;i++){
        adj[i].push_back({i+n,d[i]});
        adj[i+n].push_back({i,d[i]});
    }
    long long ans = 1e18;
    for(int i = 0;i<n;i++){
        vector<int> circle;
        vector<int> circle_edges;
        for(int j = i;j<n;j++){
            {
                circle.clear();
                circle_edges.clear();
                for(int c = i;c<=j;c++){
                    circle.push_back(c);
                    if(c != i)
                        circle_edges.push_back(l[c-1]);
                }
                circle_edges.push_back(nwedge);
                adj[i].push_back({j,nwedge});
                adj[j].push_back({i,nwedge});
                ans = min(ans,get_ans(circle,circle_edges));
                adj[i].pop_back();
                adj[j].pop_back();
            }
        }
    }
    return ans;
}

Compilation message (stderr)

shortcut.cpp: In function 'long long int get_ans(std::vector<int>, std::vector<int>)':
shortcut.cpp:33:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   33 |     for(int i = 1;i<circle.size();i++){
      |                   ~^~~~~~~~~~~~~~
shortcut.cpp:43:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   43 |     for(int i = 0;i<circle.size();i++){
      |                   ~^~~~~~~~~~~~~~
shortcut.cpp:44:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   44 |         while(pt1 + 1 < circle.size() && (d[pt1+1] - d[i]) < circle_length - (d[pt1 + 1] - d[i])){
      |               ~~~~~~~~^~~~~~~~~~~~~~~

• Subtask 1: 9 / 9
• Subtask 2: 14 / 14
• Subtask 3: 8 / 8
• Subtask 4: 7 / 7
• Subtask 5: 0 / 33
• Subtask 6: 0 / 22
• Subtask 7: 0 / 4
• Subtask 8: 0 / 3