hdoj薛猫猫杯程序设计网络赛1003 球球大作战

思路：

二分，check函数不是很好写。

实现：

1.

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll INF = 0x3f3f3f3f3f3f3f3f;
ll a[100005];
int n, k;
bool check(ll x)
{
    int cnt = 0;
    ll sum = 0;
    for (int i = 1; i <= n; i++)
    {
        if (a[i] >= x) continue;
        sum = a[i++];
        while (i <= n && sum < x)
        {
            sum += a[i++]; cnt++;
        }
        if (i > n && sum < x) cnt++;
        i--;
    }
    return cnt <= k;
}
int main()
{
    int T;
    cin >> T;
    while (T--)
    {
        ll l = INF, r;
        cin >> n >> k;
        for (int i = 1; i <= n; i++) 
        {
            cin >> a[i];
            l = min(l, a[i]);
            r += a[i];
        }
        ll ans = l;
        while (l <= r)
        {
            ll m = l + r >> 1;
            if (check(m))
            {
                ans = m;
                l = m + 1;
            }
            else r = m - 1;
        }
        cout << ans << endl;
    }
    return 0;
}

2.

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll INF = 0x3f3f3f3f3f3f3f3f;
ll a[100005], b[100005];
int n, k;
bool check(ll x)
{
    for (int i = 1; i <= n; i++) b[i] = a[i];
    int cnt = 0;
    for (int i = 1; i <= n; i++)
    {
        if (b[i] >= x) continue;
        b[i + 1] += b[i];
        cnt++;
    }
    return cnt <= k;
}
int main()
{
    int T;
    cin >> T;
    while (T--)
    {
        ll l = INF, r;
        cin >> n >> k;
        for (int i = 1; i <= n; i++) 
        {
            cin >> a[i];
            l = min(l, a[i]);
            r += a[i];
        }
        ll ans = l;
        while (l <= r)
        {
            ll m = l + r >> 1;
            if (check(m))
            {
                ans = m;
                l = m + 1;
            }
            else r = m - 1;
        }
        cout << ans << endl;
    }
    return 0;
}