题目2 : Longest Repeated Sequence

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 ... an (0 <= ai <= 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

求解

判断时，要注意的是子串不能重叠。

另外，以下代码是暴力求解的，没有在比赛中提交过。

#include <iostream>
#include <cstdio>
using namespace std;
int func(char* str, int len) {
    int rst = 0;
    int m, n, length;
    for(int i = 0; i != len - 1; ++i)
        for(int span = 1; span != len - i; ++span) {
            length = 0;
            for(m = i, n = i + span; length != span && str[m] == str[n]; ++m, ++n, ++length);
            rst = length > rst ? length : rst;
        }
    return rst;
}
int main(){
    int N;
    char* str = new char[N];
    scanf("%d", &N);
    for(int i = 0; i != N; ++i)
        cin >> str[i];
    cout << func(str, N) << endl;
    delete[] str;
    return 0;
}