Suppose these three people are Xiao Ming, Xiao Hei and Xiao Hong. Each of them has many gifts. According to the requirements of the topic, there are three possibilities: Xiaohe and Xiaohong give gifts to each other, Xiaohe and Xiaoming give gifts to each other, and Xiaoming and Xiaohong give gifts to each other, that is, every two people give gifts in three ways.

Extended data:

Addition principle is the principle of classification and counting, which is often used for permutation and combination. Specifically, there are n ways to do something, the first way is M 1, the second way is M2, …, and the nth way is Mn, so there are M 1+M2+…+Mn ways to do it.

Addition principle and multiplication principle are two basic principles, and the difference between them is that one is related to classification and the other is related to gradual progress. The key to applying the above two principles lies in proper classification and reasonable step by step.

Classification must include all situations, and should not be overlapped and duplicated, and should be classified according to the same standard; Step by step, each step should be completed in turn to ensure the completion of the whole event, and there can be no redundancy, repetition or lack of a step.