problem
1640. Check Array Formation Through Concatenation
solution#1:
code
solution#2:
code
solution#3:
code
参考
1. leetcode_essy_sort_1640. Check Array Formation Through Concatenation;
完
【leetcode_easy_sort】1640. Check Array Formation Through Concatenation
原文：https://www.cnblogs.com/happyamyhope/p/14071763.html