LeetCode 18. Letter Combinations of a Phone Number
依题意做即可,输入为2-9间的数字。代码:classSolution
{
public:
vectorletterCombinations(stringdigits)
{
vectorret(1,"");
stringletters[]={"abc","def","ghi","jkl","mno","pqrs","tuv","wxyz"};
for(size_ti=0;i=0;--j)
{
fo