Cod sursa(job #785496)

Utilizator round1First Round round1 Data 9 septembrie 2012 11:21:12
Problema Arbori indexati binar Scor 0
Compilator cpp Status done
Runda Arhiva educationala Marime 1.15 kb
#include <cstdio>
#include <algorithm>
using namespace std;
#define Max 100001
int a[Max],n;

void update(int idx,int val)
{
    while(idx <= n)
    {
        a[idx] += val;
        idx += idx & -idx;
    }
}

int suma(int idx)
{
    int sum = 0;
    while(idx > 0)
    {
        sum += a[idx];
        idx -= idx & -idx;
    }
    return sum;
}

int cbin(int x)
{
    int l = 1,r = n,m;
    while(l < r)
    {
        m = (l+r)/2;
        if(suma(m) >= x)r = m; else l = m+1;
    }
    return suma(l) == x ? l : -1;
}

int main()
{
    int m,c,x,y;
    freopen("test.in","r",stdin);
    freopen("test.out","w",stdout);
        scanf("%d %d",&n,&m);
        for(int i=1;i<=n;i++)
        {
            scanf("%d",&x);
            update(i,x);
        }
        while(m--)
        {
            scanf("%d",&c);
            if(c == 2)
            {
                scanf("%d",&x);
                printf("%d\n",cbin(x));
            } else {
                scanf("%d %d",&x,&y);
                if(c == 0) update(x,y); else
                printf("%d\n",suma(y)-suma(x-1));
            }
        }
    return 0;
}