Submission #646855

#	Time	Username	Problem	Language	Result	Execution time	Memory
646855		DobromirAngelov	Sum Zero (RMI20_sumzero)	C++14	61 / 100	569 ms	50688 KiB

sumzero

#include<bits/stdc++.h>
#define endl '\n'
using namespace std;

const int MAXN=4e5+5;
const int INF=1e9+5;

int n,q;
int a[MAXN];
long long pref[MAXN];
int nxt[MAXN];
int prv[20][MAXN];
map<int,int> m;

int main()
{
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);

cin>>n;
for(int i=1;i<=n;i++) cin>>a[i];

for(int i=1;i<=n;i++)
{
    pref[i]=pref[i-1]+a[i];//cout<<pref[i]<<" ";
}//cout<<endl;
for(int i=n;i>=0;i--)
{
    if(!m[pref[i]]) nxt[i]=INF; ///
    else nxt[i]=m[pref[i]];
    m[pref[i]]=i;
    //cout<<nxt[i]<<" ";
}//cout<<endl;
int ptr=n;
///memset(prv,-1,sizeof(prv));
for(int i=n;i>=0;i--)
{
    while(ptr>=nxt[i])
    {
        prv[0][ptr]=i+1;
        ptr--;
    }
}
for(;ptr>=0;ptr--) prv[0][ptr]=-1;
//for(int i=1;i<=n;i++) cout<<prv[0][i]<<" "; cout<<endl;
int log_n;
for(int i=1;(1<<i)<=n;i++)
{
    for(int j=1;j<=n;j++)
    {
        if(prv[i-1][j]>1) prv[i][j]=prv[i-1][prv[i-1][j]-1];
        else prv[i][j]=-1;
        //cout<<prv[i][j]<<" ";
    }//cout<<endl;
    if(prv[i][n]==-1) break;
    log_n=i;
}

cin>>q;
for(int i=0;i<q;i++)
{
    int l,r;
    cin>>l>>r;
    int j=log_n;
    int ans=0;
    for(;;)
    {
        if(l>r || j<0) break;
        if(prv[j][r]>=l)
        {
            ans+=(1<<j);
            r=prv[j][r]-1;
        }
        j--; ///
    }
    cout<<ans<<endl;
}

return 0;
}

Compilation message (stderr)

sumzero.cpp: In function 'int main()':
sumzero.cpp:72:20: warning: 'log_n' may be used uninitialized in this function [-Wmaybe-uninitialized]
   72 |             ans+=(1<<j);
      |                  ~~^~~~

• Subtask 1: 22 / 22
• Subtask 2: 39 / 39
• Subtask 3: 0 / 39