View Compilation Error

0_0_29093849_17906.cpp: In function 'int main()':
0_0_29093849_17906.cpp:108:19: error: 'strlen' was not declared in this scope
   int len=strlen(s);
                   ^
0_0_29093849_17906.cpp:139:29: error: 'memset' was not declared in this scope
   memset(vist,0,sizeof(vist));
                             ^