Submission #173596

#	Time	Username	Problem	Language	Result	Execution time	Memory
173596		juggernaut	Bigger segments (IZhO19_segments)	C++14	100 / 100	301 ms	94676 KiB

segments

//Just try and the idea will come
#include<bits/stdc++.h>
#define int long long int
#define fr first
#define sc second
using namespace std;
int pref[500001],i,n,l,r,m,sp[500001][20],logs[500001],j;
pair<int,int>dp[500001];
int get(int l,int r){
    int len=logs[r-l+1];
    return min(sp[l][len],sp[r-(1ll<<len)+1][len]);
}
main(){
    for(i=2;i<500001;i++)logs[i]=logs[i>>1]+1;
    for(i=1;i<500001;i++)
        for(j=0;j<20;j++)sp[i][j]=1e15;
    scanf("%lld",&n);
    for(i=1;i<=n;i++){
        scanf("%lld",&pref[i]);
        pref[i]+=pref[i-1];
    }
    for(i=1;i<=n;i++){
        l=0,r=i-1;
        while(l<r){
            m=(l+r+1)>>1;
            if(pref[i]>=get(m,i-1))l=m;
            else r=m-1;
        }
        dp[i]={dp[l].fr+1,pref[i]-pref[l]};
        j=1;
        sp[i][0]=dp[i].sc+pref[i];
        while(i-(1ll<<j)+1>=0){
            sp[i-(1ll<<j)+1][j]=min(sp[i-(1ll<<(j-1))+1][j-1],sp[i-(1ll<<j)+1][j-1]);
            j++;
        }
    }
    printf("%lld",dp[n].fr);
}

Compilation message (stderr)

segments.cpp:13:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
 main(){
      ^
segments.cpp: In function 'int main()':
segments.cpp:17:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%lld",&n);
     ~~~~~^~~~~~~~~~~
segments.cpp:19:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%lld",&pref[i]);
         ~~~~~^~~~~~~~~~~~~~~~~

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