Cod sursa(job #1978199)

Utilizator MaligMamaliga cu smantana Malig Data 7 mai 2017 08:02:32
Problema Arbori indexati binar Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.89 kb
#include <iostream>
#include <fstream>
#include <stack>
#include <cstdlib>
#include <ctime>

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 querySingle(int);
int findIdx(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;

        switch (tip) {
        case 0: {
            in>>a>>b;
            update(a,b);

            break;
        }
        case 1: {
            in>>a>>b;

            if (a == b) {
                out<<querySingle(a)<<'\n';
            }
            else {
                out<<query(b) - query(a-1)<<'\n';
            }

            break;
        }
        case 2: {
            in>>a;
            out<<( (a == 0) ? -1 : findIdx(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 ans = 0;
    while (idx) {
        ans += aib[idx];

        idx -= idx & (~idx + 1);
    }

    return ans;
}

int querySingle(int idx) {
    int sum1 = aib[idx],
        pre = idx - 1,
        sum2 = 0,
        lca = idx - (idx & (~idx + 1));

    while (pre != lca) {
        sum2 += aib[pre];

        pre -= pre & (~pre + 1);
    }

    return sum1 - sum2;
}

int findIdx(int sum) {
    int idx = 0,
        pw = 1;
    for (;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;
}