Cod sursa(job #2696760)

Utilizator mex7Alexandru Valentin mex7 Data 16 ianuarie 2021 15:42:29
Problema Arbori indexati binar Scor 50
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 1.44 kb
#include <bits/stdc++.h>
#define ll long long
#define cin fin
#define cout fout
using namespace std;
ifstream fin("aib.in");
ofstream fout("aib.out");
int n, m, a, b, val;
int bit[400099];

void update(int index, int add) {
    for (; index <= n; index += index & (-index))
        bit[index] += add;
}

int prefixSum(int index) {
    int result = 0;
    for (; index; index -= index & (-index))
        result += bit[index];
    return result;
}

int sumOfInterval(int a, int b) {
    return prefixSum(b) - prefixSum(a - 1);
}

int main() {
    ios :: sync_with_stdio(0);
    cin.tie(0);

    cin >> n >> m;
    for (int i = 1; i <= n; i++) {
        cin >> val;
        update(i, val);
    }

    int type;
    for (int query = 1; query <= m; query++) {
        cin >> type;

        if (!type) {
            cin >> a >> b;
            update(a, b);
        } else if (type == 1) {
            cin >> a >> b;
            cout << sumOfInterval(a, b) << '\n';
        } else {
            cin >> val;

            //binary searching for the answer
            int i, add;
            for (add = 1; add < n; add <<= 1);

            for (i = 0; add; add >>= 1)
                if (i + add <= n && prefixSum(i + add) <= val)
                    i += add;

            if (prefixSum(i) == val)
                cout << i << '\n';
            else
                cout << "-1\n";
        }
    }

    return 0;
}