Submission #970888

#	Time	Username	Problem	Language	Result	Execution time	Memory
970888		12345678	Rainforest Jumps (APIO21_jumps)	C++17	48 / 100	832 ms	73652 KiB

jumps

#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], p[kx][nx], pa[nx][kx], rt, mn[nx], mx[nx];
vector<int> d[nx], g[nx];

void dfs(int u, int p)
{
    //cout<<"dfs "<<u<<'\n';
    mn[u]=mx[u]=u;
    pa[u][0]=p;
    for (int i=1; i<kx; i++) pa[u][i]=pa[pa[u][i-1]][i-1];
    for (auto v:g[u]) dfs(v, u), mn[u]=min(mn[u], mn[v]), mx[u]=max(mx[u], mx[v]);
}

int lca(int u, int v)
{
    if (lvl[u]>lvl[v]) swap(u, v);
    for (int i=kx-1; i>=0; i--) if (lvl[pa[v][i]]>=lvl[u]) v=pa[v][i];
    if (u==v) return v;
    for (int i=kx-1; i>=0; i--) if (pa[u][i]!=pa[v][i]) u=pa[u][i], v=pa[v][i];
    return pa[u][0];
}

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);
    }
    queue<int> q;
    for (int i=0; i<N; i++) if (l[i]==N&&r[i]==N) q.push(i), rt=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++)
    {
        if (lvl[l[i]]>lvl[r[i]]) g[l[i]].push_back(i);
        else g[r[i]].push_back(i);
    }
    for (int i=0; i<kx; i++) p[i][N]=N;
    for (int i=0; i<N; i++) p[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++) p[i][j]=p[i-1][p[i-1][j]];
    dfs(rt, rt);
}

int minimum_jumps(int A, int B, int C, int D) {
    if (B<mn[C]) return -1;
    A=max(A, mn[C]);
    A=lca(A, B);
    int res=0;
    for (int i=kx-1; i>=0; i--) if (lvl[p[i][A]]>=lvl[C]) res+=(1<<i), A=p[i][A];
    return res+lvl[A]-lvl[C];
}

/*
7 6
3 2 1 6 4 5 7
1 2 5 5
1 2 6 6
0 3 6 6
1 4 6 6
2 3 4 4
4 5 6 6

*/

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