Is Subsequence

description

Given a string s and a string t, check if s is subsequence of t.

You may assume that there is only lower case English letters in both s and t. t is potentially a very long (length ~= 500,000) string, and s is a short string (<=100).

A subsequence of a string is a new string which is formed from the original string by deleting some (can be none) of the characters without disturbing the relative positions of the remaining characters. (ie, “ace” is a subsequence of “abcde” while “aec” is not).

Example 1:
s = “abc”, t = “ahbgdc”
Return true.

Example 2:
s = “axc”, t = “ahbgdc
Return false.

thinking

判断字符串是否为另一字符串的子串，只需遍历一遍即可

solution

class Solution {  public:      bool isSubsequence(string s, string t)     {          if(s.size()>t.size())             return false;          int len1 = s.size(), len2 = t.size(), k1 = 0, k2 = 0;          while(k1 < len1 && k2 < len2)          {              if(s[k1]==t[k2]) k1++;              k2++;          }          return k1 == len1;      }  };