Submission #671774

#	Time	Username	Problem	Language	Result	Execution time	Memory
671774		Vahe	Rainforest Jumps (APIO21_jumps)	C++17	0 / 100	4058 ms	17712 KiB

jumps

#include "jumps.h"
#include <iostream>
#include <algorithm>
#include <vector>
#include <stack>
using namespace std;
int n;
vector<int> h, pge, nge, dp;
vector<vector<int>> gp;
int a, b, c, d;

vector<int> PNG(vector<int> v, bool b)
{
    if (b) reverse(v.begin(), v.end());
    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);
    }
    if (b) {
        reverse(tmp.begin(), tmp.end());
        for (int& i : tmp) i = (i == -1 ? -1 : n - 1 - i);
    } 
    return tmp;
}

void dfs(int u)
{
    if (u >= c && u <= d) { dp[u] = 0; return; }
    if (dp[u] != 2e9) return;

    int x = 2e9, y = 2e9;
    if (!gp[u].empty()   ) dfs(gp[u][0]), x = dp[gp[u][0]];
    if ( gp[u].size() > 1) dfs(gp[u][1]), y = dp[gp[u][1]];

    dp[u] = min(int(2e9), min(x, y) + 1);
}

void init(int N, vector<int> H)
{
    n = N;
    h = H;
    pge = PNG(H, 0);
    nge = PNG(H, 1);
    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]);
    }
}

int minimum_jumps(int A, int B, int C, int D)
{
    a = A, b = B, c = C, d = D;
    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> PNG(std::vector<int>, bool)':
jumps.cpp:19:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   19 |     for (int i = 1; i < v.size(); i++)
      |                     ~~^~~~~~~~~~

• 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