洛谷p1182

P1182 数列分段 Section II

不知道long long不开有没有影响,left的值必须是最大的\(A_i\)

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#include<bits/stdc++.h>
using namespace std;
const int N = 100010;
int n, m;
vector<long long>a(N);
vector<long long>pre(N);

bool check(long long x) {
    long long sum = 0;
    int cnt = 1;
    for(int i = 1; i <= n; i++) {
        sum += a[i];
        if(sum > x) {
            sum = a[i];
            cnt++;
        }
    }
    return cnt <= m;
}

int main() {
    cin >> n >> m;
    long long maxa = 0;
    for(int i = 1; i <= n; i++) {
        cin >> a[i];
        maxa = max(maxa, a[i]);
        pre[i] = pre[i - 1] + a[i];
    }

    long long left = maxa, right = pre[n], ans = 0;
    while(left <= right) {
        long long mid = (left + right) / 2;
        if(check(mid)) {
            ans = mid;
            right = mid - 1;
        } else {
            left = mid + 1;
        }
    }
    cout << ans << '\n';
    return 0;
}