枚举

#include <bits/stdc++.h>
using namespace std;
int m, k;
int a[505];
bool check(int x)
{
    int cnt = 0; // 需要几个人
    int now = 0; // 当前这个人花的时间
    for (int i = 1; i <= m; i++)
    {
        // 这一本书 x 都抄不完
        if (a[i] > x)
            return false;
        // 看看前一个人能不能再抄一本书
        if (now + a[i] > x)
        {
            cnt++;
            now = a[i];
        }
        else
            now += a[i];
    }
    if (now > 0)
        cnt++;
    return cnt <= k;
}
struct Plan
{
    int l, r, tim;
};
vector<Plan> plan;
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cin >> m >> k;
    for (int i = 1; i <= m; i++)
        cin >> a[i];
    // # 找到最少时间
    // 枚举每个人花费不超过多少时间
    int ans = 0;
    for (int i = 1;; i++)
    {
        if (check(i))
        {
            ans = i;
            break;
        }
    }
    // cout << ans << "\n";
    // # 根据最少时间生成方案
    int last = m;
    int now = 0;
    for (int i = m; i >= 1; i--)
    {
        if (now + a[i] <= ans)
            now += a[i];
        else
        {
            plan.push_back((Plan){i + 1, last, now});
            now = a[i];
            last = i;
        }
    }
    plan.push_back((Plan){1, last, now});
    for (int i = (int)plan.size() - 1; i >= 0; i--)
        cout << plan[i].l << " " << plan[i].r << "\n";
    return 0;
}

二分

#include <bits/stdc++.h>
using namespace std;
int m, k;
int a[505];
bool check(int x)
{
    int cnt = 0; // 需要几个人
    int now = 0; // 当前这个人花的时间
    for (int i = 1; i <= m; i++)
    {
        // 这一本书 x 都抄不完
        if (a[i] > x)
            return false;
        // 看看前一个人能不能再抄一本书
        if (now + a[i] > x)
        {
            cnt++;
            now = a[i];
        }
        else
            now += a[i];
    }
    if (now > 0)
        cnt++;
    return cnt <= k;
}
struct Plan
{
    int l, r, tim;
};
vector<Plan> plan;
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    cin >> m >> k;
    for (int i = 1; i <= m; i++)
        cin >> a[i];
    // # 找到最少时间
    // 枚举每个人花费不超过多少时间
    int ans = 0;
    int l = 1;
    int r = 1000000000;
    while (l <= r)
    {
        int mid = (l + r) / 2;
        if (check(mid))
        {
            ans = mid;
            r = mid - 1;
        }
        else
            l = mid + 1;
    }
    // cout << ans << "\n";
    // # 根据最少时间生成方案
    int last = m;
    int now = 0;
    for (int i = m; i >= 1; i--)
    {
        if (now + a[i] <= ans)
            now += a[i];
        else
        {
            plan.push_back((Plan){i + 1, last, now});
            now = a[i];
            last = i;
        }
    }
    plan.push_back((Plan){1, last, now});
    for (int i = (int)plan.size() - 1; i >= 0; i--)
        cout << plan[i].l << " " << plan[i].r << "\n";
    return 0;
}