Submission #1025946

#	Time	Username	Problem	Language	Result	Execution time	Memory
1025946		ttamx	The short shank; Redemption (BOI21_prison)	C++17	100 / 100	317 ms	262484 KiB

prison

#include<bits/stdc++.h>

using namespace std;

const int INF=INT_MAX/2;

const int N=2e6+5;

int n,d,t,m;
int a[N],pre[N],par[N];
int ans;
pair<int,int> range[N];
vector<int> g[N];
int dep[N],cnt[N];
stack<pair<int,int>> s,st;

int dfs(int u){
    int deep=-1;
    for(auto v:g[u])if(dfs(v)>dep[u])dep[u]=dep[v],deep=v;
    for(auto v:g[u])if(v!=deep)cnt[dep[v]]++;
    return ++dep[u];
}

int main(){
    cin.tie(nullptr)->sync_with_stdio(false);
    cin >> n >> d >> t;
    for(int i=0;i<n;i++)cin >> a[i];
    s.emplace(-INF,-1);
    for(int i=0;i<n;i++){
        int x=min(a[i],t)-i;
        while(s.top().first>x)s.pop();
        if(a[i]>t)pre[i]=s.top().second;
        else pre[i]=-1,ans++;
        s.emplace(a[i]-i,i);
    }
    for(int i=0;i<n;i++)if(pre[i]!=-1)range[m++]={pre[i],i-1};
    ans+=m;
    for(int i=0;i<m;i++){
        par[i]=-1;
        int x=range[i].first;
        while(!st.empty()&&st.top().first>=x){
            int j=st.top().second;
            st.pop();
            g[i].emplace_back(j);
            par[j]=i;
        }
        st.emplace(x,i);
    }
    for(int i=0;i<m;i++)if(par[i]==-1)cnt[dfs(i)]++;
    for(int i=m;i>=0;i--)while(cnt[i]--&&d-->0)ans-=i;
    cout << ans;
}

• Subtask 1: 15 / 15
• Subtask 2: 10 / 10
• Subtask 3: 20 / 20
• Subtask 4: 10 / 10
• Subtask 5: 25 / 25
• Subtask 6: 20 / 20