Cod sursa(job #2808425)

Utilizator rares89_Dumitriu Rares rares89_ Data 25 noiembrie 2021 00:28:44
Problema Arbori indexati binar Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.14 kb
#include <fstream>

using namespace std;

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

int n, aib[100005], q, c, x, y;

void update(int ii, int val) {
    for(int i = ii; i <= n; i += (i & -i)) {
        aib[i] += val;
    }
}

int query(int ii) {
    int s = 0;
    for(int i = ii; i > 0; i -= (i & -i)) {
        s += aib[i];
    }
    return s;
}

int cb(int x) {
    int st = 1, dr = n;
    while(st <= dr) {
        int m = (st + dr) / 2;
        int a = query(m);
        if(a == x) {
            return m;
        } else if(a < x) {
            st = m + 1;
        } else {
            dr = m - 1;
        }
    }
    return -1;
}

int main() {
    fin >> n >> q;
    for(int i = 1; i <= n; i++) {
        fin >> x;
        update(i, x);
    }
    for(int i = 1; i <= q; i++) {
        fin >> c;
        if(c == 0) {
            fin >> x >> y;
            update(x, y);
        } else if(c == 1) {
            fin >> x >> y;
            fout << query(y) - query(x - 1) << "\n";
        } else if(c == 2) {
            fin >> x;
            fout << cb(x) << "\n";
        }
    }
    return 0;
}