# | Time | Username | Problem | Language | Result | Execution time | Memory |
---|---|---|---|---|---|---|---|
1223370 | SpyrosAliv | Rainforest Jumps (APIO21_jumps) | C++20 | 0 ms | 0 KiB |
#include "jumps.h"
#include <bits/stdc++.h>
using namespace std;
const int INF = 1e9;
int n;
vector<int> h;
vector<int> toL, toR;
vector<vector<int>> g, revG;
vector<int> deg;
void init(int N, vector<int> H) {
n = N;
h = {0};
toL.assign(n+1, 0);
toR.assign(n+1, 0);
for (auto x: H) h.push_back(x);
stack<int> st;
for (int i = 1; i <= n; i++) {
while (!st.empty() && h[st.top()] <= h[i]) st.pop();
if (st.empty()) toL[i] = 0;
else toL[i] = st.top();
st.push(i);
}
while (!st.empty()) st.pop();
for (int i = n; i >= 1; i--) {
while (!st.empty() && h[st.top()] <= h[i]) st.pop();
if (st.empty()) toR[i] = n+1;
else toR[i] = st.top();
st.push(i);
}
deg.assign(n+1, 0);
revG.resize(n+1);
g.resize(n+1);
for (int i = 1; i <= n; i++) {
if (toL[i] >= 1) {
g[i].push_back(toL[i]);
revG[toL[i]].push_back(i);
deg[i]++;
}
if (toR[i] <= n) {
g[i].push_back(toR[i]);
revG[toR[i]].push_back(i);
deg[i]++;
}
}
}
int minimum_jumps(int a, int b, int c, int d) {
a++;
b++;
c++;
d++;
queue<int> q;
vector<int> currDeg = deg;
for (int i = 1; i <= n; i++) {
if (currDeg[i] == 0) q.push(i);
}
vector<int> dp(n+1, INF);
while (!q.empty()) {
int curr = q.front();
q.pop();
if (curr >= c && curr <= d) dp[curr] = 0;
for (auto next: g[curr]) {
dp[curr] = min(dp[curr], 1 + dp[next]);
}
for (auto next: revG[curr]) {
currDeg[next]--;
if (currDeg[next] == 0) q.push(next);
}
}
int mn = INF;
for (int i = a; i <= b; i++) {
mn = min(mn, dp[i]);
}
if (mn == INF) return -1;
else return mn;
}
int main() {
cin >> n;
vector<int> H(n);
for (int i = 0; i < n; i++) cin >> H[i];
init(n, H);
int a, b, c, d; cin >> a >> b >> c >> d;
cout << minimum_jumps(a, b, c, d) << "\n";
}