【LeetCode】58. Length of Last Word

题目描述

Given a string s consists of upper/lower-case alphabets and empty space characters ’ ‘, return the length of last word in the string.

If the last word does not exist, return 0.

Note: A word is defined as a character sequence consists of non-space characters only.

For example, Given s = “Hello World“, return 5.

解题思路

从后往前，从第一个非空格的字符开始，找到第一个空格或者字符串的开头为止。

AC代码

class Solution { public: int lengthOfLastWord(string s) { if (s.empty()) return 0; int startIdx = s.size() - 1; // strip the final space for (; startIdx >= 0; --startIdx) { if (s[startIdx] != ' ') break; } if (startIdx < 0) return 0; for (int i = startIdx; i >= 0; --i) { if (s[i] == ' ') return startIdx - i; } return startIdx + 1; } };