View Compilation Error

0_0_35123712_2528.cpp: In function 'int find_shortest_path()':
0_0_35123712_2528.cpp:64:31: error: 'memset' was not declared in this scope
     memset(dist,0,sizeof(dist));
                               ^
0_0_35123712_2528.cpp: In function 'int backtrack(int)':
0_0_35123712_2528.cpp:105:83: error: 'strlen' was not declared in this scope
         if (find_shortest_path() && dist[endx*2+1][endy*2+1]/2 == (int)strlen(path)) { // solution found
                                                                                   ^
In file included from 0_0_35123712_2528.cpp:2:0:
0_0_35123712_2528.cpp: In function 'int main()':
0_0_35123712_2528.cpp:197:27: error: 'strlen' was not declared in this scope
         assert(strlen(path) <= (DIMENSION-1)*5);
                           ^
0_0_35123712_2528.cpp:228:43: error: 'memset' was not declared in this scope
                 memset(flag,0,sizeof(flag));
                                           ^