View Compilation Error

0_0_16304060_13671.cpp: In function 'int main()':
0_0_16304060_13671.cpp:42:28: error: 'memset' was not declared in this scope
    memset(vis,0,sizeof(vis));
                            ^
0_0_16304060_13671.cpp:52:19: error: 'strlen' was not declared in this scope
     end=s[strlen(s)-1]-'a';
                   ^