在ACM的题目中经常会遇到大数相加和相乘的问题，在有些公司的面试题中也有暗含要用大数才能解决的问题。比如：输入三个整数，写一个程序判断这个三个整数能否构成一个直角三角形。此题算法很简单，但是却暗含着结果可能溢出的问题。如果不会用大数，此题就无法给出完美的答案。-ACM topic often encounter large numbers addition and multiplication problems, some face questions implied use of large numbers in order to solve the problem. For example: Enter three integers, write a program to determine the three integers ability to form a right triangle. This question is very simple algorithm, but implies the result may overflow. If not with the large numbers, this question can not be given the perfect answer.