Submission #729260

#	Time	Username	Problem	Language	Result	Execution time	Memory
729260		grogu	Shortcut (IOI16_shortcut)	C++14	0 / 100	2 ms	724 KiB

shortcut

#include "shortcut.h"
#include <bits/stdc++.h>
#define endl '\n'
#define here cerr<<"=========================================\n"
#define dbg(x) cerr<<#x<<": "<<x<<endl;
#define ll long long
#define pb push_back
#define popb pop_back
#define all(a_) a_.begin(),a_.end()
#define pll pair<ll,ll>
#define sc second
#define fi first
#define llinf 1000000000000000LL
#define ceri(a,l,r) {cerr<<#a<<": ";for(ll i = l;i<=r;i++) cerr<<a[i]<< " ";cerr<<endl;}

using namespace std;
#define maxn 2005
int n,tsz;
ll c;
vector<pair<int,ll> > g[maxn];
vector<int> cyc;
vector<ll> ps;
ll cyclen;
bool naso = 0;
bool inc[maxn];
ll len[maxn][maxn];
ll dept[maxn];
ll mx[maxn][2];
ll cur;
void dfs2(int u,int par){
    mx[u][0] = mx[u][1] = -llinf;
    if(g[u].size()==1) mx[u][0] = 0;
    for(pair<int,ll> p : g[u]){
        int s = p.fi;
        ll w = p.sc;
        if(inc[s]) continue;
        if(s==par) continue;
        dept[s] = dept[u] + w;
        dfs2(s,u);
        vector<ll> v;
        v.pb(mx[s][0] + w);
        v.pb(mx[s][0] + w);
        v.pb(mx[u][0]);
        v.pb(mx[u][1]);
        cur = max(cur,mx[u][0] + mx[s][0] + w);
        sort(all(v));
        mx[u][0] = v[3];
        mx[u][1] = v[2];
    }
}
ll dis[maxn];
void dfs3(int u,int par){
    for(pair<int,ll> p : g[u]){
        ll s = p.fi;
        ll w = len[u][s];
        if(s==par) continue;
        dis[s] = dis[u] + w;
        dfs3(s,u);
    }
}
ll naj(ll x){
    for(ll i = 1;i<=tsz;i++) dis[i] = llinf;
    dis[x] = 0;
    dfs3(x,x);
    ll ans = x;
    for(ll i = 1;i<=tsz;i++) if(dis[i]>dis[ans]) ans = i;
    return ans;
}
ll find_shortcut(int N, vector<int> L, vector<int> D, int C)
{
    n = N;
    tsz = n;
    c = C;
    for(int i = 0;i<n;i++) if(D[i]) tsz++;
    for(int i = 1;i<n;i++){
        g[i].pb({i+1,L[i-1]});
        g[i+1].pb({i,L[i-1]});
        len[i][i+1] = len[i+1][i] = L[i-1];
    }
    tsz = n;
    for(int i = 1;i<=n;i++) if(D[i-1]){
        g[i].pb({++tsz,D[i-1]});
        g[tsz].pb({i,D[i-1]});
        len[i][tsz] = len[tsz][i] = D[i-1];
    }
    ll ans = llinf;
    for(int i = 1;i<=n;i++){
        for(int j = i+2;j<=n;j++){
            g[i].pb({j,c});
            g[j].pb({i,c});
            len[i][j] = len[j][i] = c;
            cyclen = 0;
            cyc.clear();
            ps.clear();
            ps.pb(0);
            for(int k = i;k<=j;k++) cyc.pb(k),inc[k] = 1;
            for(int k = 1;k<cyc.size();k++) ps.pb(ps[k-1] + len[cyc[k]][cyc[k-1]]);
            cyclen = ps.back() + len[cyc[0]][cyc.back()];
            ps.pb(cyclen);
            for(int k = 1;k<cyc.size();k++) ps.pb(ps.back() + len[cyc[k]][cyc[k-1]]);
            cur = 0;
            int m = ps.size()-1;
            for(int k = 0;k<cyc.size();k++){
                ll y = cyc[k];
                dfs2(y,y);
                if(g[y].size()==2) mx[y][0] = 0;
            }
            int f = 0;
            deque<pll> q;
            for(int e = 0;e<cyc.size();e++){
                while(f<ps.size()-1&&ps[f+1]-ps[e]<=cyclen/2){
                    f++;
                    ll val = mx[cyc[f%(cyc.size())]][0] + ps[f];
                    while(q.size()&&val>q.back().fi) q.popb();
                    q.pb({val,f});
                }
                cur = max(cur,mx[cyc[e%(cyc.size())]][0] - ps[e] + q.front().fi);
                if(q.front().sc==e+1) q.pop_front();
            }
            for(ll x : cyc) inc[x] = 0;
            ans = min(ans,cur);
            len[i][j] = len[j][i] = llinf;
            g[i].popb();
            g[j].popb();
        }
    }
    for(int i = 1;i<n;i++){
        len[i][i+1] = len[i+1][i] = min((ll)L[i-1],c);
        int x = naj(1);
        int y = naj(x);
        ans = min(ans,dis[y]);
        len[i][i+1] = len[i+1][i] = L[i-1];
    }
    return ans;
}
/**
4 10
10 20 20
0 40 0 30

9 30
10 10 10 10 10 10 10 10
20 0 30 0 0 40 0 40 0

3 3
1 1
1 1 1

5 1
1 1 1 1
0 0 0 0 0
**/

Compilation message (stderr)

shortcut.cpp: In function 'long long int find_shortcut(int, std::vector<int>, std::vector<int>, int)':
shortcut.cpp:97:28: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   97 |             for(int k = 1;k<cyc.size();k++) ps.pb(ps[k-1] + len[cyc[k]][cyc[k-1]]);
      |                           ~^~~~~~~~~~~
shortcut.cpp:100:28: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  100 |             for(int k = 1;k<cyc.size();k++) ps.pb(ps.back() + len[cyc[k]][cyc[k-1]]);
      |                           ~^~~~~~~~~~~
shortcut.cpp:103:28: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  103 |             for(int k = 0;k<cyc.size();k++){
      |                           ~^~~~~~~~~~~
shortcut.cpp:110:28: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  110 |             for(int e = 0;e<cyc.size();e++){
      |                           ~^~~~~~~~~~~
shortcut.cpp:111:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  111 |                 while(f<ps.size()-1&&ps[f+1]-ps[e]<=cyclen/2){
      |                       ~^~~~~~~~~~~~
shortcut.cpp:102:17: warning: unused variable 'm' [-Wunused-variable]
  102 |             int m = ps.size()-1;
      |                 ^

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