foo.cpp: In function 'void input_data()':
foo.cpp:16:39: error: expression cannot be used as a function
 reach[i][j]=((x1[i]-x2[j])(x1[i]-x2[j])+(y1[i]-y2[j])(y1[i]-y2[j]))<=(k*k);//reach[i][j]??i??????j??????
                                       ^
foo.cpp:16:66: error: expression cannot be used as a function
 reach[i][j]=((x1[i]-x2[j])(x1[i]-x2[j])+(y1[i]-y2[j])(y1[i]-y2[j]))<=(k*k);//reach[i][j]??i??????j??????
                                                                  ^
foo.cpp: In function 'void search_ans(int, int)':
foo.cpp:85:17: error: name lookup of 'i' changed for ISO 'for' scoping [-fpermissive]
 search_ans(used,i+1);
                 ^
foo.cpp:85:17: note: (if you use '-fpermissive' G++ will accept your code)
foo.cpp: At global scope:
foo.cpp:87:7: error: expected constructor, destructor, or type conversion before '(' token
 memcpy(a,tempa,sizeof(a));
       ^
foo.cpp:88:7: error: expected constructor, destructor, or type conversion before '(' token
 memcpy(b,tempb,sizeof(b));
       ^
foo.cpp:89:1: error: expected declaration before '}' token
 }
 ^