Leetcode 365. Water and Jug Problem

You are given two jugs with capacities x and y litres. There is an infinite amount of water supply available. You need to determine whether it is possible to measure exactly z litres using these two jugs.

If z liters of water is measurable, you must have z liters of water contained within one or both buckets by the end.

Operations allowed:

Fill any of the jugs completely with water.
Empty any of the jugs.
Pour water from one jug into another till the other jug is completely full or the first jug itself is empty.
Example 1: (From the famous “Die Hard” example)

Input: x = 3, y = 5, z = 4
Output: True
Example 2:

Input: x = 2, y = 6, z = 5
Output: False

用 gcd 求出 x 和 y 的最大公約數，z 若能整除最大公約數則爲true

class Solution {
    private:
        int gcd(int a,int b){
            return b==0?a:gcd(b,a%b);
        }
    public:
        bool canMeasureWater(int x, int y, int z) {
            return z==0||(z<=x+y&&z%gcd(x,y)==0);
        }
};