Is this a triangle? -- 7kyu

原题http://www.codewars.com/kata/is-this-a-triangle/train/cpp

题目

Implement a method that accepts 3 integer values a, b, c. The method should return true if a triangle can be built with the sides of given length and false in any other case.
(In this case, all triangles must have surface greater than 0 to be accepted).

分析

*三边构成三角形条件：都要满足两边之和大于第三边，两边之差小于第三边并且边需要大于0，所以负数和0排除需要那么就可以推导出两种判断方式：
1.A + b> C和A + C> b和b + C> A
2.ab

代码

namespace Triangle{  bool isTriangle(int a, int b, int c)  {  return a-b<c && b-c<a && c-a<b;  }};

namespace Triangle{  bool isTriangle(int a, int b, int c)  {    long la(a),lb(b),lc(c);    return a>0 and b>0 and c>0 and           la-lb<lc and la-lc<lb and lb-lc<la and           la+lb>lc and la+lc>lb and lb+lc>la;        }};作者：jdzhangxin链接：http://www.jianshu.com/p/ccbbaa81a9db來源：简书著作权归作者所有。商业转载请联系作者获得授权，非商业转载请注明出处。