제출 #356266

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
356266		achibasadzishvili	Islands (IOI08_islands)	C++17	30 / 100	881 ms	131072 KiB

islands

#include<bits/stdc++.h>
#define ll long long
#define f first
#define s second
#define pb push_back
#define mp make_pair
#define N 1000002
using namespace std;
int n,p[N],l[N],fix[N],F[N],k,c[N],len;
long long mx[N],ans,pas;
vector<pair<int,int> >v[N];
vector<int>g,all,dis;
void dfs(int x){
    if(F[x])return;
    all.pb(x);
    F[x] = 1;
    for(int i=0; i<v[x].size(); i++)
        dfs(v[x][i].f);
}
void findc(int x,int par){
    if(fix[x]){
        g.pb(x);
        dis.pb(l[par]);
        k = 1;
        return;
    }
    g.pb(x);
    fix[x] = 1;
    for(int i=0; i<v[x].size(); i++)
        if(v[x][i].s != par){
            dis.pb(l[v[x][i].s]);
            findc(v[x][i].f , v[x][i].s);
            if(k)return;
            dis.pop_back();
        }
    g.pop_back();
}
void findmx(int x,int par){
    for(int i=0; i<v[x].size(); i++){
        if(v[x][i].s != par && !c[v[x][i].f]){
            findmx(v[x][i].f , v[x][i].s);
            ans = max(ans , mx[x] + mx[v[x][i].f] + l[v[x][i].s]);
            mx[x] = max(mx[x] , mx[v[x][i].f] + l[v[x][i].s]);
        }
    }
}
main(){
    ios::sync_with_stdio(false);
    cin >> n;
    
    for(int i=1; i<=n; i++){
        cin >> p[i] >> l[i];
        v[p[i]].pb(mp(i , i));
        v[i].pb(mp(p[i] , i));
    }
    ll cur,cur2,pre;
    for(int s=1; s<=n; s++){
        if(F[s])continue;
        len = 0;
        ans = 0;
        k = 0;
        all.clear();
        dfs(s);
        g.clear();
        dis.clear();
        findc(s , 0);
        vector<int>cyc,d;
        for(int i=0; i<g.size(); i++){
            if(g[i] == g[(int)g.size() - 1]){
                for(int j=i+1; j<g.size(); j++){
                    cyc.pb(g[j]);
                    d.pb(dis[j - 1]);
                    c[g[j]] = 1;
                }
                break;
            }
        }
        for(int i=0; i<cyc.size(); i++){
            findmx(cyc[i] , 0);
            len += d[i];
        }
        cur = mx[cyc[0]];
        cur2 = mx[cyc[0]];
        pre = 0;
        for(int i=1; i<cyc.size(); i++){
            pre += d[i];
            ans = max(ans , cur + mx[cyc[i]] + pre);
            ans = max(ans , cur2 + len + mx[cyc[i]] - pre);
            cur = max(cur , mx[cyc[i]] - pre);
            cur2 = max(cur2 , mx[cyc[i]] + pre);
        }
        pas += ans;
    }
    
    cout << pas << '\n';
    
}

컴파일 시 표준 에러 (stderr) 메시지

islands.cpp: In function 'void dfs(int)':
islands.cpp:17:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   17 |     for(int i=0; i<v[x].size(); i++)
      |                  ~^~~~~~~~~~~~
islands.cpp: In function 'void findc(int, int)':
islands.cpp:29:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   29 |     for(int i=0; i<v[x].size(); i++)
      |                  ~^~~~~~~~~~~~
islands.cpp: In function 'void findmx(int, int)':
islands.cpp:39:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   39 |     for(int i=0; i<v[x].size(); i++){
      |                  ~^~~~~~~~~~~~
islands.cpp: At global scope:
islands.cpp:47:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   47 | main(){
      |      ^
islands.cpp: In function 'int main()':
islands.cpp:68:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   68 |         for(int i=0; i<g.size(); i++){
      |                      ~^~~~~~~~~
islands.cpp:70:33: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   70 |                 for(int j=i+1; j<g.size(); j++){
      |                                ~^~~~~~~~~
islands.cpp:78:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   78 |         for(int i=0; i<cyc.size(); i++){
      |                      ~^~~~~~~~~~~
islands.cpp:85:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   85 |         for(int i=1; i<cyc.size(); i++){
      |                      ~^~~~~~~~~~~

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