Cod sursa(job #2711321)

Utilizator divianegoescuDivia Negoescu divianegoescu Data 23 februarie 2021 22:22:39
Problema Arbori indexati binar Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 0.98 kb
#include <fstream>
using namespace std;
ifstream fin("aib.in");
ofstream fout("aib.out");
int n,a[100100],i,x,q,op,poz,y;
int lsb(int x){
    return x&-x;
}
void update(int i,int x){
    for(;i<=n;i+=lsb(i))
        a[i]+=x;
}
int query(int i){
    int sum=0;
    for(;i;i-=lsb(i))
        sum+=a[i];
    return sum;
}
int cbin(int val){
    int st=1,dr=n,mid;
    while(st<=dr){
        mid=(st+dr)/2;
        if(query(mid)>=val)
            dr=mid-1;
        else st=mid+1;
    }
    if(query(st)!=val)
        return -1;
    return st;
}
int main(){
    fin>>n>>q;
    for(i=1;i<=n;i++){
        fin>>x;
        update(i,x);
    }
    for(;q--;){
        fin>>op;
        if(op==0){
            fin>>poz>>x;
            update(poz,x);
        }
        if(op==1){
            fin>>x>>y;
            fout<<query(y)-query(x-1)<<"\n";
        }
        if(op==2){
            fin>>x;
            fout<<cbin(x)<<"\n";
        }
    }
    return 0;
}