Submission #1273727

#	Time	Username	Problem	Language	Result	Execution time	Memory
1273727		nguyenbaoanh	Sum Zero (RMI20_sumzero)	C++20	0 / 100	2 ms	1336 KiB

sumzero

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ii pair<int,int>

const int N = 200005;
const int LOG = 20;

int n, q;
ll a[N], pre[N];
int nxt[N], up[N][LOG];
int cnt[N][LOG]; // cnt[i][k] = số đoạn khi nhảy 2^k lần từ i

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

    cin >> n;
    for(int i=1; i<=n; i++){
        cin >> a[i];
        pre[i] = pre[i-1] + a[i];
    }

    // build nxt[]
    unordered_map<ll,int> mp;
    for(int i=n; i>=0; i--){ // duyệt cả pre[0]
        if(mp.count(pre[i])){
            nxt[i] = mp[pre[i]];
        }else nxt[i] = -1;
        mp[pre[i]] = i;
    }

    // build up[][], cnt[][]
    for(int i=0; i<=n; i++){
        if(nxt[i] != -1){
            up[i][0] = nxt[i];
            cnt[i][0] = 1;
        }else{
            up[i][0] = i+1;
            cnt[i][0] = 0;
        }
    }
    up[n+1][0] = n+1; cnt[n+1][0] = 0;

    for(int k=1; k<LOG; k++){
        for(int i=0; i<=n+1; i++){
            up[i][k] = up[ up[i][k-1] ][k-1];
            cnt[i][k] = cnt[i][k-1] + cnt[ up[i][k-1] ][k-1];
        }
    }

    cin >> q;
    while(q--){
        int l,r; cin >> l >> r;
        l--; // vì ta làm trên pre[]
        int pos = l, res = 0;
        for(int k=LOG-1; k>=0; k--){
            if(up[pos][k] <= r){
                res += cnt[pos][k];
                pos = up[pos][k];
            }
        }
        cout << res << "\n";
    }
    return 0;
}

• Subtask 1: 0 / 22
• Subtask 2: 0 / 39
• Subtask 3: 0 / 39