poj3104 Drying

思路：

二分。

实现：

#include <cstdio>
#include <algorithm>
using namespace std;
typedef long long ll;
const int MAXN = 100005;
int a[MAXN], n, k;
int Ceil(int a, int c)
{
    return (a + c - 1) / c;
}
bool check(int x)
{
    ll tot = 0;
    for (int i = 0; i < n; i++)
    {
        if (a[i] > x) tot += Ceil(a[i] - x, k - 1);
        if (tot > x) return false;
    }
    return true;
}
int main()
{
    scanf("%d", &n);
    int maxn = 0;
    for (int i = 0; i < n; i++) 
    { 
        scanf("%d", &a[i]); 
        maxn = max(maxn, a[i]); 
    }
    scanf("%d", &k);
    if (k == 1) { printf("%d
", maxn); return 0; }
    int l = 1, r = maxn, ans = maxn;
    while (l <= r)
    {
        int m = (l + r) >> 1;
        if (check(m))
        {
            ans = m; r = m - 1;
        }
        else l = m + 1;
    }
    printf("%d
", ans);
    return 0;
}