Submission #695287

#TimeUsernameProblemLanguageResultExecution timeMemory
695287stevancvRabbit Carrot (LMIO19_triusis)C++14
0 / 100
4 ms5040 KiB
#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define sp ' '
#define en '\n'
#define smin(a, b) a = min(a, b)
#define smax(a, b) a = max(a, b)
using namespace std;
const int N = 2e5 + 2;
const ll linf = 1e18;
ll a[N];
int l[N], r[N], dp[N];
vector<int> g[N];
int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int n;
    ll k;
    cin >> n >> k;
    for (int i = 1; i <= n; i++) {
        cin >> a[i];
        a[i] -= k * i;
    }
    a[n + 1] = -linf;
    stack<int> s;
    for (int i = 0; i <= n + 1; i++) {
        while (!s.empty() && a[s.top()] < a[i]) s.pop();
        if (!s.empty()) l[i] = s.top();
        else l[i] = -1;
        s.push(i);
    }
    while (!s.empty()) s.pop();
    for (int i = n + 1; i >= 0; i--) {
        while (!s.empty() && a[s.top()] > a[i]) s.pop();
        if (!s.empty()) r[i] = s.top();
        else r[i] = -1;
        s.push(i);
    }
    for (int i = 0; i <= n + 1; i++) {
        if (l[i] != -1) g[i].push_back(l[i]);
        if (r[i] != -1) g[r[i]].push_back(i);
    }
    for (int i = 1; i <= n + 1; i++) {
        dp[i] = n;
        for (int j : g[i]) smin(dp[i], dp[j] + i - j - 1);
    }
    cout << dp[n + 1] << en;
    return 0;
}
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