题目链接：http://codeforces.com/contest/766/problem/A
题目：
A. Mahmoud and Longest Uncommon Subsequence
time limit per test
2 seconds
memory limit per test
256 megabytes
input
standard input
output
standard output
While Mahmoud and Ehab were practicing for IOI, they found a problem which name was Longest common subsequence. They solved it, and then Ehab challenged Mahmoud with another problem.
Given two strings a and b, find the length of their longest uncommon subsequence, which is the longest string that is a subsequence of one of them and not a subsequence of the other.
A subsequence of some string is a sequence of characters that appears in the same order in the string, The appearances don't have to be consecutive, for example, strings "ac", "bc", "abc" and "a" are subsequences of string "abc" while strings "abbc" and "acb" are not. The empty string is a subsequence of any string. Any string is a subsequence of itself.
Input
The first line contains string a, and the second line — string b. Both of these strings are non-empty and consist of lowercase letters of English alphabet. The length of each string is not bigger than 105 characters.
Output
If there's no uncommon subsequence, print "-1". Otherwise print the length of the longest uncommon subsequence of a and b.
Examples
Input
abcd
defgh
Output
5
Input
a
a
Output
-1
Note
In the first example: you can choose "defgh" from string b as it is the longest subsequence of string b that doesn't appear as a subsequence of string a.
题目大意：
给你两个字符串，求这两个字符串的最长不公共子串的长度
题目分析：
相信做过dp46的小伙伴们第一反应想到的就是dp了，但是仔细想想这题很简单啊，完全不需要用dp，两个字符串，如果这两个字符串相等，那么彼此包含，肯定就不存在不公共子串，反之，如果两个字符串都不想等，那么A串一定就不是B串的子串啊，取两者较大的输出
AC代码：
#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<algorithm>
using namespace std;
const int maxn=1e5+5;
char s1[maxn],s2[maxn];
int l1,l2;
int main()
{
while(~scanf("%s%s",s1,s2))
{
l1=strlen(s1);
l2=strlen(s2);
int q=strcmp(s1,s2)==0?-1:max(l1,l2);
cout<<q<<endl;
}
return 0;
}