제출 #1198446

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1198446		TheSahib	Bigger segments (IZhO19_segments)	C++20	0 / 100	0 ms	324 KiB

segments

#include <bits/stdc++.h>
using namespace std;
using int64 = long long;

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

    int N;
    cin >> N;
    vector<int64> a(N);
    for(int i = 0; i < N; i++){
        cin >> a[i];
    }

    // 1) compute prefix sums S[0..N]
    vector<int64> S(N+1, 0);
    for(int i = 1; i <= N; i++){
        S[i] = S[i-1] + a[i-1];
    }

    // 2) best[d] = smallest prefix-sum at which we can form d segments
    const int64 INF = (int64)4e18;
    // we need up to N+1 entries
    vector<int64> best(N+2, INF);
    best[0] = 0;  // zero segments at sum 0

    int answer = 0;
    // 3) for each position i, find max d with best[d] <= S[i]
    for(int i = 1; i <= N; i++){
        int lo = 0, hi = i;
        // binary search for largest d in [0..i] with best[d] <= S[i]
        while(lo < hi){
            int mid = (lo + hi + 1) >> 1;
            if(best[mid] <= S[i]) lo = mid;
            else hi = mid - 1;
        }
        int d = lo;
        answer = max(answer, d);
        // update best[d+1]
        if(best[d+1] > S[i]){
            best[d+1] = S[i];
        }
    }

    cout << answer << "\n";
    return 0;
}

• Subtask 1: 0 / 13
• Subtask 2: 0 / 14
• Subtask 3: 0 / 10
• Subtask 4: 0 / 36
• Subtask 5: 0 / 27