Subsequences Summing to Sevens

Subsequences Summing to Sevens The title describes farmer John's N cows is standing in a row, as they has a tendency to does from time to time. Each cow are labeled with a distinct an 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 Numbe Rs 1 ... 6, he is 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. Enter the first line of input contains N (1≤n≤50,000). The next n lines each contain the N-integer IDs of the cows (all is in the range 0 ... 1,000,000). Output 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.

Want to note the sum of the IDs of a large group of cows might is too large to fit into a standard 32-bit int Eger. If you is summing up large groups of IDs, the therefore want to use a larger the integer data type, like a 64-bit "long l Ong "in C + +. Sample input

7351621410

Sample output

5

Tips

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

Analysis: (I+J)%k=i%k, then J is a multiple of k;

Code:

#include <iostream>#include<cstdio>#include<cstdlib>#include<cmath>#include<algorithm>#include<climits>#include<cstring>#include<string>#include<Set>#include<map>#include<queue>#include<stack>#include<vector>#include<list>#include<bitset>#defineRep (I,m,n) for (i=m;i<=n;i++)#defineRSP (It,s) for (Set<int>::iterator It=s.begin (); It!=s.end (); it++)#defineVI vector<int>#definePII pair<int,int>#defineMoD 1000000007#defineINF 0x3f3f3f3f#definePB Push_back#defineMP Make_pair#defineFi first#defineSe Second#definell Long Long#definePi ACOs (-1.0)Const intmaxn=1e6+Ten;Const intdis[4][2]={{0,1},{-1,0},{0,-1},{1,0}};using namespacestd;ll gcd (ll p,ll q) {returnq==0? P:GCD (q,p%q);} ll Qpow (ll p,ll q) {ll F=1; while(q) {if(q&1) f=f*p;p=p*p;q>>=1;}returnF;}intn,m;ll a[maxn],pre[7],last[7],now;intMain () {inti,j,k,t; scanf ("%d",&N); Rep (I,1, N) {scanf ("%lld",&A[i]); now= (Now+a[i])%7; if(Pre[now]) last[now]=i; Elsepre[now]=i; } ll Ma=0; Rep (I,0,6)    {        if(Pre[i]&&last[i]) Ma=max (ma,last[i]-Pre[i]); } printf ("%lld\n", MA); //System ("pause");    return 0;}

Subsequences Summing to Sevens