Submission #145004

#	Time	Username	Problem	Language	Result	Execution time	Memory
145004		evpipis	Cat in a tree (BOI17_catinatree)	C++14	100 / 100	105 ms	20344 KiB

catinatree

#include <bits/stdc++.h>
using namespace std;

#define fi first
#define se second
#define mp make_pair
#define pb push_back
typedef pair<int, int> ii;

const int len = 2e5+5;
int n, d, dis[len], opt[len];
vector<int> adj[len];

bool comp(int a, int b){
    return (dis[a] < dis[b]);
}

void dfs(int u){
    //printf("dfs: u = %d\n", u);
    for (int j = 0; j < adj[u].size(); j++){
        int v = adj[u][j];
        dfs(v);
        dis[v]++;
    }

    sort(adj[u].begin(), adj[u].end(), comp);

    opt[u] = 1;
    dis[u] = 0;
    int sum = 0;
    for (int j = 0; j < adj[u].size(); j++){
        int v = adj[u][j];
        opt[u] += opt[v];
        if (dis[v] < d)
            opt[u]--;

        sum += opt[v];
    }

    for (int i = (int)adj[u].size()-1, j = 0; i >= 0; i--){
        int v = adj[u][i];
        while (j < adj[u].size() && dis[adj[u][j]] < d-dis[v])
            j++;

        int dis2 = dis[v], opt2 = sum-i;
        if (j > i)
            opt2 = sum-(j-1);

        if (mp(opt2, dis2) > mp(opt[u], dis[u]))
            opt[u] = opt2, dis[u] = dis2;
    }
}

int main(){
    scanf("%d %d", &n, &d);
    for (int i = 1; i < n; i++){
        int temp;
        scanf("%d", &temp);
        adj[temp].pb(i);
    }

    dfs(0);

    printf("%d\n", opt[0]);
    return 0;
}

Compilation message (stderr)

catinatree.cpp: In function 'void dfs(int)':
catinatree.cpp:20:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int j = 0; j < adj[u].size(); j++){
                     ~~^~~~~~~~~~~~~~~
catinatree.cpp:31:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int j = 0; j < adj[u].size(); j++){
                     ~~^~~~~~~~~~~~~~~
catinatree.cpp:42:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         while (j < adj[u].size() && dis[adj[u][j]] < d-dis[v])
                ~~^~~~~~~~~~~~~~~
catinatree.cpp: In function 'int main()':
catinatree.cpp:55:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d %d", &n, &d);
     ~~~~~^~~~~~~~~~~~~~~~~
catinatree.cpp:58:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d", &temp);
         ~~~~~^~~~~~~~~~~~~

• Subtask 1: 11 / 11
• Subtask 2: 40 / 40
• Subtask 3: 49 / 49