╰︶￣ 莫等闲

本文摘自 LeetCode 题解3 1. Next PermutationImplement next permutation, which rearranges numbers into the lexicographically next greater permutation of numbers.If such arrangement is not possible, it must rea

康托展开的公式：（不用记，看形势就行，下面会有例子）X=an*(n-1)!+an-1*(n-2)!+...+ai*(i-1)!+...+a2*1!+a1*0!ai为整数，并且0适用范围：没有重复元素的全排列第一类题：N个数的第k个排序，例子，1，2，3，4共有4！种排列，1234,1243,1324等等。按顺序应该是12341243132413421