Submission #300136

#	Time	Username	Problem	Language	Result	Execution time	Memory
300136		Hehehe	Dreaming (IOI13_dreaming)	C++14	100 / 100	111 ms	19188 KiB

dreaming

#include<bits/stdc++.h> //:3
using namespace std;
typedef long long ll;
#define DIM 100010
#define INF 2000000000
#include "dreaming.h"
#define pi pair<int, int>

const int N = 1e5 + 11;
const ll inf = 2e9;
int path[N], viz[N], s[N], dp_up[N], dp_down[N], nr;

vector<pi> v[N];
vector<int> c[N];

void dfs (int nod, int tata){
    viz[nod] = 1;
    c[nr].push_back(nod);
    for (int i=0;i<v[nod].size();i++){
        int vecin = v[nod][i].first;
        if (vecin != tata){
            dfs (vecin,nod);
            s[nod] = max (s[nod],s[vecin]+v[nod][i].second);
        }}
    int maxim = 0, maxim2 = 0;
    for (int i=0;i<v[nod].size();i++){
        int vecin = v[nod][i].first, cost = v[nod][i].second;
        if (vecin == tata)
            continue;
        if (s[vecin]+cost > maxim){
            maxim2 = maxim;
            maxim = s[vecin]+cost;
        } else {
            if (s[vecin]+cost > maxim2)
                maxim2 = s[vecin]+cost;
        }}
    dp_down[nod] = maxim+maxim2;
}
void dfs2 (int nod, int tata, int cost){

    dp_up[nod] = max (dp_up[nod],dp_up[tata]+cost);
    int maxim = 0, maxim2 = 0, p = 0;
    for (int i=0;i<v[nod].size();i++){
        int fiu = v[nod][i].first, cst = v[nod][i].second;
        if (fiu == tata)
            continue;
        if (s[fiu]+cst > maxim){
            maxim2 = maxim;
            maxim = s[fiu]+cst, p = fiu;
        } else
            if (s[fiu]+cst > maxim2)
                maxim2 = s[fiu]+cst;
    }
    for (int i=0;i<v[nod].size();i++){
        int fiu = v[nod][i].first;
        if (fiu == tata)
            continue;
        if (fiu == p)
            dp_up[fiu] = max (dp_up[fiu],maxim2+v[nod][i].second);
        else dp_up[fiu] = max (dp_up[fiu],maxim+v[nod][i].second);
    }

    for (int i=0;i<v[nod].size();i++){
        int vecin = v[nod][i].first;
        if (vecin != tata)
            dfs2 (vecin,nod,v[nod][i].second);
    }}

int travelTime (int n, int m, int l, int a[], int b[], int cost[]){

    for(int i = 0; i <= n; i++){
        v[i].clear();
    }

    for(int i = 0; i < m; i++){
        int x = a[i], y = b[i], z = cost[i];
        x++, y++;
        v[x].push_back({y, z});
        v[y].push_back({x, z});
    }

    memset(viz,0,sizeof(viz));
    memset(dp_up,0,sizeof(dp_up));
    memset(dp_down,0,sizeof(dp_down));
    memset(s,0,sizeof(s));

    for(int i = 1; i <= n; i++){
        if(viz[i])continue;

        nr++;
        dfs(i, 0);
        dfs2(i, 0, 0);
    }

    int ans = 0;
    for(int i = 1;i <= nr; i++){
        int mn = inf;
        for(auto nod : c[i]){
            int dist_max = max(dp_up[nod] + s[nod], dp_down[nod]);
            ans = max(ans, dist_max);
            int dist = max(s[nod], dp_up[nod]);
            mn = min(mn,dist);
        }
        path[i] = mn;
    }

    sort(path + 1, path + nr + 1);

    if(nr >= 2)ans = max(ans, path[nr] + path[nr - 1] + l);
    if(nr >= 3)ans = max(ans, path[nr - 1] + path[nr - 2] + 2*l);

    return ans;
}

Compilation message (stderr)

dreaming.cpp: In function 'void dfs(int, int)':
dreaming.cpp:19:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   19 |     for (int i=0;i<v[nod].size();i++){
      |                  ~^~~~~~~~~~~~~~
dreaming.cpp:26:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   26 |     for (int i=0;i<v[nod].size();i++){
      |                  ~^~~~~~~~~~~~~~
dreaming.cpp: In function 'void dfs2(int, int, int)':
dreaming.cpp:43:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   43 |     for (int i=0;i<v[nod].size();i++){
      |                  ~^~~~~~~~~~~~~~
dreaming.cpp:54:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   54 |     for (int i=0;i<v[nod].size();i++){
      |                  ~^~~~~~~~~~~~~~
dreaming.cpp:63:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   63 |     for (int i=0;i<v[nod].size();i++){
      |                  ~^~~~~~~~~~~~~~

• Subtask 1: 14 / 14
• Subtask 2: 10 / 10
• Subtask 3: 23 / 23
• Subtask 4: 18 / 18
• Subtask 5: 12 / 12
• Subtask 6: 23 / 23