View Compilation Error

0_0_38768372_2976.cpp: In function 'double judge(int, int)':
0_0_38768372_2976.cpp:31:22: error: 'sqrt' was not declared in this scope
   31 |         double dis = sqrt(1.0 * (xx[x] - xx[y]) * (xx[x] - xx[y]) + 1.0 * (yy[x] - yy[y]) * (yy[x] - yy[y]));
      |                      ^~~~