Young Physicist - Implementation

class Vector3D
 x, y, z
 
 constructor(x, y, z)
 this.x := x
 this.y := y
 this.z := z
 
 method add(other)
 this.x := this.x + other.x
 this.y := this.y + other.y
 this.z := this.z + other.z
 
 method isZero()
 return (this.x = 0 AND this.y = 0 AND this.z = 0)

function check_equilibrium(n, forces)
 sum := new Vector3D(0, 0, 0)
 for each force in forces
 sum.add(force)
 if sum.isZero() then
 return "YES"
 else
 return "NO"
``` . The time complexity is $O(n)$ where $n$ is the number of forces.