#LUOGUP2174. [USACO16JAN] Subsequences Summing to Sevens S

[USACO16JAN] Subsequences Summing to Sevens S

题目描述

Farmer John's NN cows are standing in a row, as they have a tendency to do from time to time. Each cow is labeled with a distinct integer ID number so FJ can tell them apart. FJ would like to take a photo of a contiguous group of cows but, due to a traumatic childhood incident involving the numbers 161 \ldots 6, he only wants to take a picture of a group of cows if their IDs add up to a multiple of 7.

Please help FJ determine the size of the largest group he can photograph.

给你n个数,分别是a[1],a[2],...,a[n]。求一个最长的区间[x,y],使得区间中的数(a[x],a[x+1],a[x+2],...,a[y-1],a[y])的和能被7整除。输出区间长度。若没有符合要求的区间,输出0。

输入格式

The first line of input contains NN (1N50,0001 \leq N \leq 50,000). The next NN

lines each contain the NN integer IDs of the cows (all are in the range

01,000,0000 \ldots 1,000,000).

输出格式

Please output the number of cows in the largest consecutive group whose IDs sum

to a multiple of 7. If no such group exists, output 0.

7
3
5
1
6
2
14
10
5

提示

In this example, 5+1+6+2+14 = 28.