Submission #718664

#	Time	Username	Problem	Language	Result	Execution time	Memory
718664		lam	Rainforest Jumps (APIO21_jumps)	C++14	0 / 100	3 ms	5072 KiB

jumps

#include "jumps.h"
#include <bits/stdc++.h>
#include <vector>
using namespace std;
const int maxn = 2e5 + 10;
int n,d[maxn];
int a[maxn];
vector <int> adj[maxn];
int par[20][maxn];
int in[maxn],out[maxn],rt,cnt;

void dfs(int x, int p, int dep=0)
{
    par[0][x] = p;
    in[x]=++cnt;
    d[x]=dep;
    for (int i=1; i<20; i++) par[i][x]=par[i-1][par[i-1][x]];
    for (int i:adj[x])
        dfs(i,x,dep+1);
    out[x]=cnt;
}

bool check(int u, int v)
{
    return in[u]<=in[v]&&out[v]<=out[u];
}

int lca(int u, int v)
{
    if (check(u,v)) return u;
    if (check(v,u)) return v;
    for (int i=19; i>=0; i--)
        if (!check(par[i][u],v)) u=par[i][u];
    return par[0][u];
}

void addedge(int u, int v)
{
    adj[u].push_back(v);
}
void init(int N, std::vector<int> H) {
    n=N;
    for (int i=0; i<n; i++) a[i]=H[i],adj[i].clear();
    deque<int> dq;
    for (int i=0; i<n; i++)
    {
        while (!dq.empty()&&a[dq.back()] < a[i]) dq.pop_back();
        if (!dq.empty()) addedge(i,dq.back());
        dq.push_back(i);
    }
    while (!dq.empty()) dq.pop_back();
    for (int i=n-1; i>=0; i--)
    {
        while (!dq.empty()&&a[dq.back()] < a[i]) dq.pop_back();
        if (!dq.empty()) addedge(i,dq.back());
        dq.push_back(i);
    }
    rt=-1;
    for (int i=0; i<n; i++) if (rt==-1||a[i]>a[rt]) rt=i;
    cnt=0;
    dfs(rt,rt);
}

int minimum_jumps(int A, int B, int C, int D) {
    if (lca(A,C)!=C) return -1;
    return d[A]-d[C];
}

• Subtask 1: 0 / 4
• Subtask 2: 0 / 8
• Subtask 3: 0 / 13
• Subtask 4: 0 / 12
• Subtask 5: 0 / 23
• Subtask 6: 0 / 21
• Subtask 7: 0 / 19