以下这个解法也是参考了一些讨论：

https://leetcode.com/discuss/110235/c-solution-using-euclidean-algorithm

还有这个解释原理的，没有看懂：https://leetcode.com/discuss/110525/a-little-explanation-on-gcd-method

 

class Solution {    int gcd(int a, int b) {        // below suppose a <= b        // and if b < a, then b%a == b        return a==0?b:gcd(b%a, a);    }public:    bool canMeasureWater(int x, int y, int z) {        // notice, operator priority: % > == > && > ||        // so below is equivalent to        // (z == 0) || ((z <= (x+y)) && ((z % gcd(x,y)) == 0))        return z == 0 || z <= (x+y) && z % gcd(x, y) == 0;    }};

31 / 31 test cases passed.	Status:  Accepted
Runtime: 0 ms