Submission #885904

#	Time	Username	Problem	Language	Result	Execution time	Memory
885904		dimashhh	Bigger segments (IZhO19_segments)	C++17	100 / 100	262 ms	58240 KiB

segments

#include <bits/stdc++.h>

using namespace std;
const int N = 1e6 + 1,MOD = 998244353;
typedef long long ll;
#define int long long
int n,a[N];
ll dp[N],mn[N],pref[N];
mt19937 rng(123321);

struct node{
    node *l = 0,*r = 0;
    ll mx,val,prior,key;
    node(ll key,ll val):key(key),val(val),mx(val),prior(rng()){}
};
using pnode = node *;
ll mx(pnode f){
    return (f ? f->mx : 0);
}
void upd(pnode &f){
    f->mx = max({f->val,mx(f->l),mx(f->r)});
}
pnode merge(pnode a,pnode b){
    if(!a) return b;
    if(!b) return a;
    if(a->prior > b->prior){
        a->r = merge(a->r,b);
        upd(a);
        return a;
    }else{
        b->l = merge(a,b->l);
        upd(b);
        return b;
    }
}
pair<pnode,pnode> split(pnode x,int val){
    if(!x) return {0,0};
    if(x->key <= val){
        auto [a,b] = split(x->r,val);
        x->r = a;
        upd(x);
        return {x,b};
    }else{
        auto [a,b] = split(x->l,val);
        x->l = b;
        upd(x);
        return {a,x};
    }
}
pnode root = NULL;
void insert(ll key,ll val){
    pnode nv = new node(key,val);
    auto [x,y] = split(root,key);
    root = merge(x,merge(nv,y));
}
void test(){
    cin >> n;
    for(int i = 1;i <= n;i++){
        cin >> a[i];
        pref[i] = pref[i - 1] + a[i];
    }
    insert(0,0);    
    for(int i = 1;i <=n;i++){
        ll cur = 0;
        auto [x,y] = split(root,pref[i]);
        // if(!x) continue;
        ll val = x->mx;
        dp[i] = dp[val] + 1;
        mn[i] = pref[i] - pref[val];
        root = merge(x,y);
        insert(mn[i] + pref[i],i);
        // for(int j = i;j >= 1;j--){
        //     if(mn[j - 1] + pref[j - 1] <= pref[i]){
        //         if(dp[j - 1] + 1 > dp[i]){
        //             dp[i] = dp[j - 1] +1;
        //             mn[i] = pref[i] - pref[j - 1];
        //         }
        //     }
        // }
    }
    cout << dp[n];
}
signed main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int T = 1;
    // cin >> T;
    test();
}

Compilation message (stderr)

segments.cpp: In constructor 'node::node(ll, ll)':
segments.cpp:13:21: warning: 'node::key' will be initialized after [-Wreorder]
   13 |     ll mx,val,prior,key;
      |                     ^~~
segments.cpp:13:11: warning:   'll node::val' [-Wreorder]
   13 |     ll mx,val,prior,key;
      |           ^~~
segments.cpp:14:5: warning:   when initialized here [-Wreorder]
   14 |     node(ll key,ll val):key(key),val(val),mx(val),prior(rng()){}
      |     ^~~~
segments.cpp:13:11: warning: 'node::val' will be initialized after [-Wreorder]
   13 |     ll mx,val,prior,key;
      |           ^~~
segments.cpp:13:8: warning:   'll node::mx' [-Wreorder]
   13 |     ll mx,val,prior,key;
      |        ^~
segments.cpp:14:5: warning:   when initialized here [-Wreorder]
   14 |     node(ll key,ll val):key(key),val(val),mx(val),prior(rng()){}
      |     ^~~~
segments.cpp: In function 'void test()':
segments.cpp:64:12: warning: unused variable 'cur' [-Wunused-variable]
   64 |         ll cur = 0;
      |            ^~~
segments.cpp: In function 'int main()':
segments.cpp:87:9: warning: unused variable 'T' [-Wunused-variable]
   87 |     int T = 1;
      |         ^

• Subtask 1: 13 / 13
• Subtask 2: 14 / 14
• Subtask 3: 10 / 10
• Subtask 4: 36 / 36
• Subtask 5: 27 / 27