Submission #126247

#	Time	Username	Problem	Language	Result	Execution time	Memory
126247		ksmzzang2003	Race (IOI11_race)	C++14	0 / 100	10 ms	9720 KiB

race

#include "race.h"
#include <bits/stdc++.h>
using namespace std;
typedef pair <int,int> pii;
int N,K,L[200003];
int par[200003],sz[200003];
vector <pii> adj[200003];
int check[1000003];
bool del[200003];
int ans = 1987654321;
vector <pii> lazy;
vector <int> usecheck;
int dfs1(int now,int prev)
{
    bool reaf=true;
    for(int i=0; i<adj[now].size(); i++)
    {
        int next = adj[now][i].first;
        int cost = adj[now][i].second;
        if(next == prev)
            continue;
        if(del[next])
            continue;
        reaf = false;
        sz[now] += dfs1(next,now);
    }
    return ++sz[now];
}

int find_cen(int now,int prev)
{
    for(int i=0; i<adj[now].size(); i++)
    {
        int next = adj[now][i].first;
        int cost = adj[now][i].second;
        if(next == prev)
            continue;
        if(del[next])
            continue;
        if(sz[next]*2>sz[now])
            return find_cen(next,now);
    }
    return now;
}

int dfs2(int now,int prev,int sum,int depth)
{
    int ret = 1987654321;
    if(sum>K)
        return 1987654321;
    if(check[K-sum]!=-1)
        ret= min(ret,depth + check[K-sum]);
    lazy.push_back(pii(sum,depth));
    for(int i=0; i<adj[now].size(); i++)
    {
        int next = adj[now][i].first;
        int cost = adj[now][i].second;
        if(next == prev)
            continue;
        if(del[next])
            continue;
        ret = min(ret,dfs2(next,now,sum+cost,depth+1));
        if(sum==0)
        {
            for(pii &it:lazy)
                check[it.first] = it.second,usecheck.push_back(it.first);
            lazy.clear();
        }
    }
    return ret;
}

void g(int now,int prev)
{
    memset(sz,0,sizeof(sz));
    dfs1(now,-1);
    int cen = find_cen(now,-1);
    for(int &it:usecheck)
        check[it] = -1;
    usecheck.clear();
    check[0] = 0;
    lazy.clear();
    ans = min(ans,dfs2(cen,-1,0,0));
    del[cen] = true;
    for(int i=0; i<adj[cen].size(); i++)
    {
        int next = adj[cen][i].first;
        int cost = adj[cen][i].second;
        if(next == prev)
            continue;
        if(del[next])
            continue;
        g(next,now);
    }
}

int best_path(int n, int k, int h[][2], int l[])
{
    memset(check,-1,sizeof(check));
    N= n ;
    K = k;
    for(int i=0; i<N-1; i++)
    {
        adj[h[i][0]].push_back(pii(h[i][1],l[i]));
        adj[h[i][1]].push_back(pii(h[i][0],l[i]));
    }
    g(2,-1);
    return (ans>=1987654300)?-1:ans;
}

Compilation message (stderr)

race.cpp: In function 'int dfs1(int, int)':
race.cpp:16:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0; i<adj[now].size(); i++)
                  ~^~~~~~~~~~~~~~~~
race.cpp:19:13: warning: unused variable 'cost' [-Wunused-variable]
         int cost = adj[now][i].second;
             ^~~~
race.cpp:15:10: warning: variable 'reaf' set but not used [-Wunused-but-set-variable]
     bool reaf=true;
          ^~~~
race.cpp: In function 'int find_cen(int, int)':
race.cpp:32:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0; i<adj[now].size(); i++)
                  ~^~~~~~~~~~~~~~~~
race.cpp:35:13: warning: unused variable 'cost' [-Wunused-variable]
         int cost = adj[now][i].second;
             ^~~~
race.cpp: In function 'int dfs2(int, int, int, int)':
race.cpp:54:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0; i<adj[now].size(); i++)
                  ~^~~~~~~~~~~~~~~~
race.cpp: In function 'void g(int, int)':
race.cpp:85:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0; i<adj[cen].size(); i++)
                  ~^~~~~~~~~~~~~~~~
race.cpp:88:13: warning: unused variable 'cost' [-Wunused-variable]
         int cost = adj[cen][i].second;
             ^~~~

• Subtask 1: 0 / 9
• Subtask 2: 0 / 12
• Subtask 3: 0 / 22
• Subtask 4: 0 / 57