UVa 714 - Copying Books

“最大值最小化”问题，先二分求最大值，再贪心实现按最左边区间最小的格式输出 。

代码如下：

#include<iostream>
#include<cstdlib>
#include<cstring>
#include<cstdio>
#include<cmath>

using namespace std;

int main()
{
#ifdef test
    freopen("in.txt", "r", stdin);
#endif
    int a[505], b[505];
    int k, m, num;
    scanf("%d", &num);
    while(num--)
    {
        long long left = 0, right = 0, ct, to, mid;
        memset(b, 0, sizeof(b));
        scanf("%d%d", &m, &k);
        for(int i = 0; i < m; i++)
        {
            scanf("%d", &a[i]);
            right += a[i];
        }
        while(left < right)    // 二分求最大值
        {
            ct = 0, to = 0;
            mid = (left + right) / 2;
            for(int i = 0; i < m; i++)
            {
                to += a[i];
                if(a[i] > mid)  // 当单个元素大于中值时，需增大mid的值
                {
                    ct = k;     // 使其跳出
                    break;
                }
                if(to >= mid)
                {
                    if(ct >= k)
                        break;
                    ct++;
                    to = a[i];
                }
            }
            if(ct > k - 1)
                left = mid + 1;
            else
                right = mid;
        }
        for(int cct = 0, tot =0, i = m - 1; i >= 0; i--)  // 贪心
        {
            tot += a[i];
            if(a[i] > mid)    //二分求最大值时可能有一点小误差，当单个元素略大于最大值时，用此更新最大值
                mid = a[i];
            if(cct < k - 1 && (tot > mid || i < (k - 1) - cct)) // 区间值大于最大值或是所剩元素与所剩区间数相等时都需划分
            {
                b[i] = 1;
                tot = a[i];
                ++cct;
            }

        }
        for(int i = 0; i < m; i++)
        {
            printf("%d%c", a[i], i != m-1 ? ' ' : '\n');
            if(b[i])
                printf("/ ");

        }
    }
    return 0;
}