Cod sursa(job #1975485)

Utilizator MaligMamaliga cu smantana Malig Data 1 mai 2017 08:23:31
Problema Arbori indexati binar Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.74 kb
#include <iostream>
#include <fstream>
#include <stack>

using namespace std;
ifstream in("aib.in");
ofstream out("aib.out");

const int NMax = 1e5 + 5;

int N,M;
int aib[NMax];

void update(int,int);
int query(int);
int readSingle(int);
int findK(int);

int main() {
    in>>N>>M;

    for (int i=1;i<=N;++i) {
        int val;
        in>>val;

        update(i,val);
    }

    while (M--) {
        int tip,a,b;
        in>>tip;
        if (!tip) {
            in>>a>>b;
            update(a,b);
        }
        else if (tip == 1) {
            in>>a>>b;
            if (a == b) {
                out<<readSingle(a)<<'\n';
            }
            else {
                out<<query(b) - query(a-1)<<'\n';
            }
        }
        else {
            in>>a;
            out<<( (a == 0) ? -1 : findK(a))<<'\n';
        }
    }

    in.close();out.close();
    return 0;
}

void update(int idx,int add) {
    while (idx <= N) {
        aib[idx] += add;
        idx += idx & (~idx + 1);
    }
}

int query(int idx) {
    int sum = 0;
    while (idx) {
        sum += aib[idx];
        idx -= idx & (~idx + 1);
    }
    return sum;
}

int readSingle(int idx) {
    int sum1 = aib[idx],
        sum2 = 0,
        pre = idx-1,
        lca = idx - (idx & (~idx + 1));
    while (pre != lca) {
        sum2 += aib[pre];
        pre -= pre & (~pre + 1);
    }
    return sum1 - sum2;
}

int findK(int sum) {
    int pw,idx = 0;
    for (pw = 1;pw <= N;pw <<= 1) ;
    pw >>= 1;

    while (pw) {
        if (idx + pw <= N && aib[idx + pw] <= sum) {
            sum -= aib[idx += pw];
        }

        pw >>= 1;
    }

    if (!sum) {
        return idx;
    }
    return -1;
}