Submission #77130

#	Time	Username	Problem	Language	Result	Execution time	Memory
77130		muradeyn	Race (IOI11_race)	C++14	0 / 100	4 ms	2680 KiB

race

#include "race.h"
#include <bits/stdc++.h>
#define intt long long
#define FAST_READ ios_base::sync_with_stdio(0);cin.tie(0);
#define SIZE 100001
#define INF INT_MAX
#define F first
#define S second
#define in(a) scanf("%d",&a);
#define outn(a) printf("%d\n",&a);
#define outs(a) printf("%d ",&a);


using namespace std;

int root , n , k , x , y , w , used[SIZE] , dp[SIZE] , co , cent = -1 , we , ans = -1;

vector< pair<int,int> >v[SIZE];

map< int , int > mp;

bool f = true;

void init() {
    for (int i = 1;i<=n;i++) {
        if (used[i] < 3 && used[i] > 0)used[i] = 0;
    }
}

void dfs(int s,int p) {
    co++;
    used[s]++;
    int sz = v[s].size();
    for (int i = 0;i<sz;i++) {
        int to = v[s][i].first;
        int cost = v[s][i].second;
        if (to == p)continue;
        if (used[to] >= 1)continue;
        we += cost;
        dfs(to,s);
    }
}

void dfs2(int s,int p) {
    used[s]++;
    dp[s] = 1;
    bool f = true;
    int sz = v[s].size();
    for (int i = 0;i<sz;i++) {
        int to = v[s][i].first;
        int cost = v[s][i].second;
        if (used[to] >= 2)continue;
        dfs2(to,s);
        if (dp[to] > co / 2) f = false;
        dp[s] += dp[to];
    }
    if (f && cent == -1 && co - dp[s] <= co / 2) cent = s;
}

void dfs3(int s,int p,int len,int cst) {
    used[s] = 1;
    if (cst == k) {
        if (ans == -1)ans = len;
        else ans = min(ans,len);
        return;
    }
    int sz = v[s].size();
    for (int i = 0;i<sz;i++) {
        int to = v[s][i].first;
        int cost = v[s][i].second;
        if (to == p)continue;
        if (used[to] >= 1)continue;
        dfs3(to,s,len + 1,cst + cost);
    }
}

void dfs4(int s,int p,int len,int cst) {
    used[s] = 2;
    bool f = false;
    if (cst > k)return;
    if (cst == k) {
        if (ans == -1)ans = len;
        else ans = min(ans,len);
        return;
    }
    else if (mp[k - cst] != 0) {
        if (ans == -1)ans = len + mp[k - cst];
        else ans = min(ans,len + mp[k - cst]);
        return;
    }
    int sz = v[s].size();
    for (int i = 0;i<sz;i++) {
        int to = v[s][i].first;
        int cost = v[s][i].second;
        if (to == p)continue;
        if (used[to] >= 2)continue;
        dfs4(to,s,len + 1,cst + cost);
    }
    if (mp[cst] == 0)mp[cst] = len;
    else if (mp[cst] > len)mp[cst] = min(mp[cst],len);
}

int best_path(int N, int K, int h[][2], int l[])
{
    k = K;
    n = N;
    for (int i = 0;i<n - 1;i++) {
        x = h[i][0];
        y = h[i][1];
        x++;
        y++;
        v[x].push_back({y,l[i]});
        v[y].push_back({x,l[i]});
    }
    while (f) {
        f = false;
        init();
        for (int i = 1;i<=n;i++) {
            if (used[i] == 0) {
              co = 0; we = 0;
                dfs(i , -1);
                if (we < k || co == 1)continue;
                dp[i] = 0;
                cent = -1;
                dfs2(i,-1);
                if (cent == -1)continue;
                f = true;
                init();
                root = cent;
                dfs3(cent,-1,0,0);
                mp.clear();
                dfs4(cent,-1,0,0);
                used[cent] = 3;
            }
        }
    }
    return ans;
}

Compilation message (stderr)

race.cpp: In function 'void dfs2(int, int)':
race.cpp:51:13: warning: unused variable 'cost' [-Wunused-variable]
         int cost = v[s][i].second;
             ^~~~
race.cpp: In function 'void dfs4(int, int, int, int)':
race.cpp:79:10: warning: unused variable 'f' [-Wunused-variable]
     bool f = false;
          ^

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