牛客网暑期多校训练第二场G题

链接：https://www.nowcoder.com/acm/contest/140/G
White Cloud placed n containers in sequence on a axes. The i-th container is located at x[i] and there are a[i] number of products in it.
White Rabbit wants to buy some products. The products which are required to be sold must be placed in the same container.
The cost of moving a product from container u to container v is 2*abs(x[u]-x[v]).
White Cloud wants to know the maximum number of products it can sell. The total cost can't exceed T.

输入描述:

The first line of input contains 2 integers n and T(n <= 500000,T <= 1000000000000000000) In the next line there are n increasing numbers in range [0,1000000000] denoting x[1..n] In the next line there are n numbers in range[0,10000] denoting a[1..n]

输出描述:

Print an integer denoting the answer.

示例1

输入

2 3
1 2
2 3

输出

4

官方做法：因为我们要让货物移动总距离尽可能小，所以最后所使用的集装箱的初始位置在数轴上一定是一段区间。 如果固定了这个区间，那么最优方案就是把这些集装箱移动到这些集装箱的坐标中位数的位置。
答案满足可二分性，先二分答案。然后我们按照从左至右的顺序枚举区间的左端点，那么区间的右端点和 区间的中位数都是单调递增的，一遍枚举一遍维护即可。 复杂度O(n*log(sum(a[i])))

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