Submission #868995

#	Time	Username	Problem	Language	Result	Execution time	Memory
868995		alexdd	Bigger segments (IZhO19_segments)	C++17	100 / 100	169 ms	26716 KiB

segments

#include<bits/stdc++.h>
using namespace std;
#define int long long
int n;
int a[500005];
int dp[500005];
int ult[500005];
int pref[500005];
signed main()
{
    cin>>n;
    for(int i=1;i<=n;i++)
    {
        cin>>a[i];
        pref[i]=pref[i-1]+a[i];
    }
    dp[0]=0;
    ult[0]=0;
    vector<int> dq;
    dq.push_back(0);
    for(int i=1;i<=n;i++)
    {
        /**dp[i]=-1;
        for(int x=i-1;x>=0;x--)
        {
            if(dp[x]+1<dp[i-1])
                break;
            if(ult[x]+pref[x]<=pref[i])
            {
                dp[i]=dp[x]+1;
                ult[i]=pref[i]-pref[x];
                break;
            }
        }*/
        int st,dr,mij;
        st=0;
        dr=(int)dq.size()-1;
        while(st<=dr)
        {
            mij=(st+dr)/2;
            if(ult[dq[mij]]+pref[dq[mij]]<=pref[i])
            {
                if(mij==(int)dq.size()-1 || ult[dq[mij+1]]+pref[dq[mij+1]] > pref[i])
                    break;
                st=mij+1;
            }
            else
                dr=mij-1;
        }
        dp[i]=dp[dq[mij]]+1;
        ult[i]=pref[i]-pref[dq[mij]];
        if(dp[i-1]>dp[i] || (dp[i-1]==dp[i] && ult[i-1]+a[i]<ult[i]))
        {
            dp[i]=dp[i-1];
            ult[i]=ult[i-1]+a[i];
        }
        while(ult[dq.back()]+pref[dq.back()] >= ult[i]+pref[i])
            dq.pop_back();
        dq.push_back(i);
    }
    cout<<dp[n];
    return 0;
}
/**

dp[i] = numarul maxime de secvente in care pot fi impartite primele i elemente
ult[i] = suma ultimei secvente din solutia pt dp[i]
dp[i] max= dp[i-1]
dp[i] max= max(dp[x]+1) pt x = 0..i-1 && ult[x] + pref[x] <= pref[i]


*/

Compilation message (stderr)

segments.cpp: In function 'int main()':
segments.cpp:50:24: warning: 'mij' may be used uninitialized in this function [-Wmaybe-uninitialized]
   50 |         dp[i]=dp[dq[mij]]+1;
      |                        ^

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