Longest Repeated Sequence【微软编程一小时-题目2】

时间限制:10000ms

单点时限:1000ms

内存限制:256MB

描述

You are given a sequence of integers, A = a₁, a₂, ... a_n. A consecutive subsequence of A (say a_i, a_i+1 ... a_j) is called a "repeated sequence" if it appears more than once in A (there exists some positive k that a_i+k = a_i, a_i+k+1 = a_i+1, ... a_j+k = a_j) and its appearances are not intersected (i + k > j).

Can you find the longest repeated sequence in A?

输入

Line 1: n (1 <= n <= 300), the length of A.
Line 2: the sequence, a₁ a₂ ... a_n (0 <= a_i <= 100).

输出

The length of the longest repeated sequence.

样例输入

5
2 3 2 3 2

样例输出

     2

#include <iostream>

using namespace std;

//判断存不存在长度为k的子串
bool isExist(int a[], int beg, int j, int size, int k)
{
    int len = 0;
    while(beg < size && j < size && a[beg++] == a[j++])
    {
        ++len;
        if(len == k)
            return true;
    }
    return false;
}

//Longest Repeated Sequence
int LRS(int arr[], int len)
{
    int k, maxlen, i, j;
    maxlen = 1;

    for(k = len / 2; k >= 2; k--)
    {
        for(i = 0; i < len - k; ++i)
        {
            for( j = i + k; j < len; ++j)
            {
                if(isExist(arr, i, j, len, k) == true)
                {
                    maxlen = k;
                    return maxlen;
                }
            }
        }
    }
    return maxlen;
}

int main()
{
    int s[301] = {0}, n;
    cin >> n;
    if(n <= 0 || n > 300)
        exit(0);
    for(int i = 0; i < n; i++) cin >> s[i];
    cout << LRS(s, n) << endl;

    return 0;
}