Submission #672729

#	Time	Username	Problem	Language	Result	Execution time	Memory
672729		Vahe	Rainforest Jumps (APIO21_jumps)	C++17	0 / 100	1 ms	336 KiB

jumps

#include "jumps.h"
#include <iostream>
#include <algorithm>
#include <vector>
#include <stack>
using namespace std;
int n, a, b, c, d;
vector<int> h, pge, nge, dp, par;
vector<bool> vis;
vector<vector<int>> gp;
bool arajitest = 1;
vector<vector<int>> up1, up2;

vector<int> pge_(vector<int> v)
{
    vector<int> tmp(v.size());
    stack<int> s;
    s.push(0);
    tmp[0] = -1;
    for (int i = 1; i < v.size(); i++)
    {
        while (!s.empty() && v[s.top()] < v[i]) s.pop();
        tmp[i] = (s.empty() ? -1 : s.top());
        s.push(i);
    }
    return tmp;
}
vector<int> nge_(vector<int> v)
{
    stack<int> s;
    vector<int> tmp(v.size(), -1);
    for (int i = 0; i < n; i++)
    {
        while (!s.empty() && v[s.top()] < v[i]) tmp[s.top()] = i, s.pop();
        s.push(i);
    }
    return tmp;
}
void dfs(int u)
{
    if (u >= c && u <= d) { dp[u] = 0; return; }
    if (dp[u] != 2e9) return;


    if (gp[u].size() > 0) dfs(gp[u][0]);
    if (gp[u].size() > 1) dfs(gp[u][1]);


    int x = (gp[u].size() > 0 ? dp[gp[u][0]] : 2e9);
    int y = (gp[u].size() > 1 ? dp[gp[u][1]] : 2e9);
    dp[u] = min(x, y) + 1;
}
void make1(int u)
{
    up1[u][0] = par[u];
    for (int i = 1; i < 20; i++) up1[u][i] = up1[up1[u][i - 1]][i - 1];


    int x = (gp[u].size() > 0 ? gp[u][0] : 2e9);
    int y = (gp[u].size() > 1 ? gp[u][1] : 2e9);
    if (min(x, y) != 2e9) make1(min(x, y));
}
void make2(int u)
{
    up2[u][0] = par[u];
    for (int i = 1; i < 20; i++) up2[u][i] = up2[up2[u][i - 1]][i - 1];


    int x = (gp[u].size() > 0 ? gp[u][0] : 2e9);
    int y = (gp[u].size() > 1 ? gp[u][1] : 2e9);
    if (max(x, y) != 2e9) make2(max(x, y));
    else if (min(x, y) != 2e9) make2(min(x, y));
}

void dfs(int u, int p)
{
    par[u] = p;
    for (int& v : gp[u])
    {
        if(v != p) dfs(v, u);
    }
}


void init(int N, vector<int> H)
{
    n = N;
    h = H;
    pge = pge_(H);
    nge = nge_(H);
    gp = vector<vector<int>>(n);
    for (int i = 0; i < n; i++)
    {
        if (pge[i] != -1) gp[i].push_back(pge[i]);
        if (nge[i] != -1) gp[i].push_back(nge[i]);
    }
    for (int i = 0; i < n; i++) if (H[i] != i + 1) arajitest = 0;
    up1 = up2 = vector<vector<int>>(n, vector<int>(20, -1));

    int m = 2e9, mn;
    for (int i = 0; i < n; i++) if (h[i] < m) { m = h[i], mn = i; }
    dfs(mn, mn);
    for (int i = 0; i < n; i++)
    {
        make1(i);
        make2(i);
    }
}


int minimum_jumps(int A, int B, int C, int D)
{
    a = A, b = B, c = C, d = D;
    if (arajitest) return C - B;
    else if (a == b && c == d) {
        int G = A, len = 0;
        for (int i = 19; i >= 0; i--)
        {
            if (up1[G][i] != 2e9 && h[up1[G][i]] <= h[C]) G = up1[G][i], len += (1 << i);
        }
        if (G == C) return len;
        for (int i = 19; i >= 0; i--)
        {
            if (up2[G][i] != 2e9 && h[up2[G][i]] <= h[C]) G = up2[G][i], len += (1 << i);
        }
        return G == C ? len : -1;
    }
    else {
        dp = vector<int>(n, 2e9);
        int mn = 2e9;
        for (int i = a; i <= b; i++) dfs(i), mn = min(mn, dp[i]);
        return (mn >= 2e9 ? -1 : mn);
    }
}

Compilation message (stderr)

jumps.cpp: In function 'std::vector<int> pge_(std::vector<int>)':
jumps.cpp:20:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   20 |     for (int i = 1; i < v.size(); i++)
      |                     ~~^~~~~~~~~~
jumps.cpp: In function 'void init(int, std::vector<int>)':
jumps.cpp:102:8: warning: 'mn' may be used uninitialized in this function [-Wmaybe-uninitialized]
  102 |     dfs(mn, mn);
      |     ~~~^~~~~~~~

• 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