A. Mahmoud and Longest Uncommon Subsequence

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.

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.

If there’s no uncommon subsequence, print “-1“. Otherwise print the length of the longest uncommon subsequence of a and b.

abcddefghOutput
5Input
aaOutput
-1Note
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.
  
題意：給兩個字符串，如果兩個字符串相等就輸出-1 反之則輸出最大的字符串長度 水題   難點就是英語太差差點看成了動態規劃
#include<stdio.h>#include<string.h>#include<algorithm>using namespace std;#define N 100005char str1[N], str2[N];int main(){    while(~scanf("%s%s",str1,str2)) {        int len1 = strlen(str1);        int len2 = strlen(str2);        if(strcmp(str1,str2))            printf("%d/n",max(len1,len2));        else            printf("-1/n");        memset(str1,0,sizeof(str1));        memset(str2,0,sizeof(str2));    }return 0;}