제출 #970763

#제출 시각아이디문제언어결과실행 시간메모리
97076312345678밀림 점프 (APIO21_jumps)C++17
0 / 100
171 ms28888 KiB
#include "jumps.h"
#include <bits/stdc++.h>

using namespace std;

const int nx=2e5+5, kx=18;

int l[nx], r[nx], deg[nx], lvl[nx], pa[kx][nx];
vector<int> d[nx];

void init(int N, std::vector<int> H) {
    stack<int> s;
    for (int i=0; i<N; i++) l[i]=r[i]=N;
    for (int i=0; i<N; i++)
    {
        while (!s.empty()&&H[s.top()]<H[i]) s.pop();
        if (!s.empty()) l[i]=s.top(), d[s.top()].push_back(i), deg[i]++;
        s.push(i);
    }
    while (!s.empty()) s.pop();
    for (int i=N-1; i>=0; i--)
    {
        while (!s.empty()&&H[s.top()]<H[i]) s.pop();
        if (!s.empty()) r[i]=s.top(), d[s.top()].push_back(i), deg[i]++;
        s.push(i);
    }
    //for (int i=0; i<N; i++) cout<<"debug "<<i<<' '<<l[i]<<' '<<r[i]<<'\n';
    queue<int> q;
    for (int i=0; i<N; i++) if (l[i]==N&&r[i]==N) q.push(i);
    while (!q.empty())
    {
        auto u=q.front();
        q.pop();
        for (auto x:d[u]) if (--deg[x]==0) q.push(x);
        lvl[u]=max(lvl[l[u]], lvl[r[u]])+1;
    }
    //for (int i=0; i<N; i++) cout<<"lvl "<<i<<' '<<lvl[i]<<'\n';
    for (int i=0; i<kx; i++) pa[i][N]=N;
    for (int i=0; i<N; i++) pa[0][i]=(lvl[l[i]]<lvl[r[i]])?l[i]:r[i];
    for (int i=1; i<kx; i++) for (int j=0; j<N; j++) pa[i][j]=pa[i-1][pa[i-1][j]];
}

int minimum_jumps(int A, int B, int C, int D) {
    int res=0;
    for (int i=kx-1; i>=0; i--) if (lvl[pa[i][A]]>=lvl[D]) res+=(1<<i), A=pa[i][A];
    if (A==D) return res;
    if (l[A]==D||r[A]==D) return res+1;
    return -1;
}
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