Cod sursa(job #1164875)

Utilizator CosminRusuCosmin Rusu CosminRusu Data 2 aprilie 2014 12:43:15
Problema Arbori indexati binar Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.47 kb
#include <fstream>
#include <iostream>

using namespace std;

const char infile[] = "aib.in";
const char outfile[] = "aib.out";

ifstream fin(infile);
ofstream fout(outfile);

const int MAXN = 100005;
const int oo = 0x3f3f3f3f;

int N, M, aib[MAXN];

inline int lsb(int x) {
    return x & (-x);
}

inline void Update(int pos, int value) {
    for(int i = pos ; i <= N ; i += lsb(i))
        aib[i] += value;
}

inline int Query(int pos) {
    int sum = 0;
    for(int i = pos ; i ; i -= lsb(i))
        sum += aib[i];
    return sum;
}

inline int binarySearch(int value) {
    int li = 1, ls = N, ans = -1;
    while(li <= ls) {
        int mid = ((li + ls) >> 1);
        int val = Query(mid);
        if(val >= value) {
            ls = mid - 1;
            if(val == value)
                ans = mid;
        }
        else li = mid + 1;
    }
    return ans;
}

int main() {
    fin >> N >> M;
    for(int i = 1;  i <= N ; ++ i) {
        int X;
        fin >> X;
        Update(i, X);
    }
    for(int i = 1 ; i <= M ; ++ i) {
        int op, a, b;
        fin >> op;
        switch(op) {
            case 0:
                fin >> a >> b;
                Update(a, b);
                break;
            case 1:
                fin >> a >> b;
                fout << Query(b) - Query(a - 1) << '\n';
                break;
            case 2:
                fin >> a;
                fout << binarySearch(a) << '\n';
                break;

        }
    }
    fout.close();
    return 0;
}