This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include <bits/stdc++.h>
using namespace std;
const int N = 200200;
const int LG = 19;
int n, l[N][LG], r[N][LG], high[N][LG];
vector<int> h;
int isValid(int x)
{
return x >= 0 && x < n;
}
void initEdges()
{
vector<pair<int, int>> sortedH;
for (int i = 0; i < n; i++)
sortedH.push_back({h[i], i});
sort(sortedH.begin(), sortedH.end(), greater<pair<int, int>>());
set<int> s;
s.insert(-1);
s.insert(n);
memset(l, -1, sizeof l);
memset(r, -1, sizeof r);
memset(high, -1, sizeof high);
for (auto [_, i] : sortedH)
{
auto it = s.lower_bound(i);
r[i][0] = *it;
l[i][0] = *(--it);
if (!isValid(l[i][0]) && !isValid(r[i][0]));
else if (!isValid(l[i][0])) high[i][0] = r[i][0];
else if (!isValid(r[i][0])) high[i][0] = l[i][0];
else if (h[l[i][0]] > h[r[i][0]]) high[i][0] = l[i][0];
else high[i][0] = r[i][0];
s.insert(i);
}
}
void constructTable()
{
for (int j = 0; j + 1 < LG; j++)
for (int i = 0; i < n; i++)
{
if (isValid(l[i][j]))
l[i][j + 1] = l[l[i][j]][j];
if (isValid(r[i][j]))
r[i][j + 1] = r[r[i][j]][j];
if (isValid(high[i][j]))
high[i][j + 1] = high[high[i][j]][j];
}
}
void init(int N, vector<int> H) {
n = N;
h = H;
h[n] = 0;
initEdges();
constructTable();
}
int jump(int &s, int table[N][LG], function<int(int)> cond)
{
int res = 0;
for (int i = LG - 1; i >= 0; i--)
{
int x = table[s][i];
if (isValid(x) && cond(x))
{
s = x;
res |= 1 << i;
}
}
return res;
}
int minimum_jumps(int A, int B, int C, int D) {
int s = B;
// find where to start
jump(s, l, [&](int x) {
return x >= A && isValid(r[x][0]) && r[x][0] <= D;
});
// use high edges as most as possible
int ans = jump(s, high, [&](int x) {
return isValid(r[x][0]) && r[x][0] < C;
});
// check if we need to go 1 more high step
if (isValid(r[s][0]) && r[s][0] < C)
{
int x = high[s][0];
if (isValid(x) && isValid(r[x][0]) && r[x][0] <= D)
{
s = x;
ans++;
}
}
// just go right
ans += jump(s, r, [&](int x) {
return x < C;
});
return r[s][0] >= C && r[s][0] <= D ? ans + 1 : -1;
}
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