Submission #173568

#	Time	Username	Problem	Language	Result	Execution time	Memory
173568		juggernaut	Bigger segments (IZhO19_segments)	C++14	13 / 100	14 ms	380 KiB

segments

//Just try and the idea will come
#include<bits/stdc++.h>
#define ll long long int
#define fr first
#define sc second
using namespace std;
ll pref[500001],i,n,l,r,m,tree[2000001],a[500001];
pair<ll,ll>dp[500001];
void update(int v,int l,int r,int pos,int val){
      if(l==pos&&r==pos){
            tree[v]=val;
            return;
      }
      int mid=(l+r)>>1;
      if(pos<=mid)update((v<<1),l,mid,pos,val);
      else update((v<<1)+1,mid+1,r,pos,val);
      tree[v]=min(tree[(v<<1)],tree[(v<<1)+1]);
}
int get(int v,int l,int r,int ql,int qr){
      if(ql<=l&&r<=qr)return tree[v];
      if(r<ql||qr<l)return 1e15;
      int mid=(l+r)>>1;
      return min(get((v<<1),l,mid,ql,qr),get((v<<1)+1,mid+1,r,ql,qr));
}
int get(int l,int r){
    ll mn=1e15;
    for(int i=l;i<=r;i++)mn=min(mn,a[i]);
    return mn;
}
int main(){
    scanf("%lld",&n);
    for(i=1;i<=n;i++){
        scanf("%lld",&pref[i]);
        pref[i]+=pref[i-1];
    }
    for(i=1;i<=n;i++){
        int l;
        for(int j=0;j<i;j++)
            if(pref[i]>=get(1,0,n,j,j))l=j;
        a[i]=dp[i].sc+pref[i];
        /*l=0,r=i-1;
        while(l<r){
            m=(l+r+1)>>1;
            if(pref[i]>=get(1,0,n,m,i-1))l=m;
            else r=m-1;
        }*/
        dp[i]={dp[l].fr+1,pref[i]-pref[l]};
        update(1,0,n,i,dp[i].sc+pref[i]);
    }
    printf("%lld",dp[n].fr);
}

Compilation message (stderr)

segments.cpp: In function 'int get(int, int, int, int, int)':
segments.cpp:21:28: warning: overflow in implicit constant conversion [-Woverflow]
       if(r<ql||qr<l)return 1e15;
                            ^~~~
segments.cpp: In function 'int main()':
segments.cpp:31:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%lld",&n);
     ~~~~~^~~~~~~~~~~
segments.cpp:33:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%lld",&pref[i]);
         ~~~~~^~~~~~~~~~~~~~~~~
segments.cpp:47:41: warning: 'l' may be used uninitialized in this function [-Wmaybe-uninitialized]
         dp[i]={dp[l].fr+1,pref[i]-pref[l]};
                                   ~~~~~~^

• Subtask 1: 13 / 13
• Subtask 2: 0 / 14
• Subtask 3: 0 / 10
• Subtask 4: 0 / 36
• Subtask 5: 0 / 27