Submission #1307908

#	Time	Username	Problem	Language	Result	Execution time	Memory
1307908		sakka	Cat Exercise (JOI23_ho_t4)	C++20	41 / 100	40 ms	9576 KiB

Main

#include <bits/stdc++.h>
#define ll long long
#define fi first
#define sec second
#define pb push_back
#define pll pair<ll,ll>
#define pii pair<int,int>
using namespace std;
void fr(){
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
}
const ll INF = 1e18;
int n, m;
vector<ll> dp(2e5+2), kiri(2e5+2), kanan(2e5+2);
vector<pll> h(2e5+2);

bool cmp(pll a, pll b){
    return a.fi > b.fi;
}
void solve(){
    cin >> n;
    for(int i=1; i<=n; i++){
        cin >> h[i].fi;
        h[i].sec = i;
    }
    vector<ll> st;
    for(int i=1; i<=n; i++){
        auto [x, idx] = h[i];
        while(st.size() && h[st.back()].fi < x){
            kanan[st.back()] = idx;
            st.pop_back();
        }
        st.pb(idx);
    }
    st.clear();
    for(int i=n; i>=1; i--){
        auto [x, idx] = h[i];
        while(st.size() && h[st.back()].fi < x){
            kiri[st.back()] = idx;
            st.pop_back();
        }
        st.pb(idx);
    }
    sort(h.begin()+1, h.begin()+n+1, cmp);
    ll mx = 0;
    dp[0] = -INF;
    for(int i=2; i<=n; i++){
        auto [x, idx] = h[i];
        dp[idx] = max(dp[kanan[idx]] + abs(idx - kanan[idx]), dp[kiri[idx]] + abs(idx - kiri[idx]));
        // cout << idx << " " << kiri[idx] << " " << kanan[idx] << endl;
        // cout << idx << " " << dp[idx] << endl;
        mx = max(mx, dp[idx]);
    }
    cout << mx << endl;
}

int main(){
    ios_base :: sync_with_stdio(0); cin.tie(0); cout.tie(0);
    // fr();
    solve();
}

Compilation message (stderr)

Main.cpp: In function 'void fr()':
Main.cpp:10:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   10 |     freopen("input.txt", "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:11:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   11 |     freopen("output.txt", "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 7 / 7
• Subtask 2: 7 / 7
• Subtask 3: 7 / 7
• Subtask 4: 0 / 10
• Subtask 5: 20 / 20
• Subtask 6: 0 / 23
• Subtask 7: 0 / 26