Cod sursa(job #2156517)

Utilizator NicuBaciuNicu Baciu NicuBaciu Data 8 martie 2018 19:42:15
Problema Arbori indexati binar Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.91 kb
#include <fstream>
#include <stdio.h>
#include <climits>

#define inc(x) ( x & (-x) )

using namespace std;

//ifstream fin("aib.in");
ofstream fout("aib.out");

int n, m;

int a[100002];
int din[100002];

FILE* f;

void read_data()
{
    fscanf(f, "%d %d", &n, &m);

    for(int i=1; i<=n; i++)
    {
        fscanf(f, "%d", &a[i]);
    }

    for(int i=1; i<=n; i++)
    {
        for(int j=i; j<=n; j+=inc(j))
            din[j]+=a[i];
    }
}

int prefsum_at(int x)
{
    int sum=0;

    for(int i=x; i>0; i-=inc(i))
        sum+=din[i];

    return sum;
}

int main()
{
    f=fopen("aib.in", "r");

    read_data();

    for(int i=1; i<=m; i++)
    {
        int op=-1;
        int x=0, y=0;

        fscanf(f, "%d", &op);

        if(op!=2)
        {
            fscanf(f, "%d %d", &x, &y);
        }
        else
        {
            fscanf(f, "%d", &x);
        }

        if(op==0)
        {
            for(int i=x; i<=n; i+=inc(i))
                din[i]+=y;
        }
        else if(op==1)
        {
            fout << prefsum_at(y) - prefsum_at(x-1) << '\n';
        }
        else if(op==2)
        {
            int st=1, dr=n, index=INT_MAX;

            while(st<dr)
            {
                int mid=(st+dr)/2;
                int ctsum=prefsum_at(mid);

                if(ctsum==x)
                {
                    index=min(index, mid);
                    dr=mid;
                }
                else if(ctsum>x)
                    dr=mid;
                else if(ctsum<x)
                    st=mid+1;
            }

            if(index==INT_MAX)
            {
                if(prefsum_at(n)==x)
                    fout << n << '\n';
                else
                    fout << "-1" << '\n';
            }
            else
                fout << index << '\n';
        }
    }

    return 0;
}