View Compilation Error

0_0_35810995_14451.cpp: In function 'void DFS(int)':
0_0_35810995_14451.cpp:26:4: error: 'b' was not declared in this scope
    b[hang] = i;
    ^
0_0_35810995_14451.cpp: In function 'int main()':
0_0_35810995_14451.cpp:42:11: error: 'b' was not declared in this scope
    memset(b,0,sizeof(b));
           ^