[Leetcode] 434. Number of Segments in a String 解题报告

题目：

Count the number of segments in a string, where a segment is defined to be a contiguous sequence of non-space characters.

Please note that the string does not contain any non-printable characters.

Example:

Input: "Hello, my name is John"Output: 5

思路：

一道练手的题目。需要注意你的代码可以覆盖各种特殊情况（例如字符串中含有两个相邻的空格，以及字符串的开头和末尾有空格等等）。算法的时间复杂度是O(n)，空间复杂度是O(1)，其中n是字符串的长度。

代码：

class Solution {public:    int countSegments(string s) {        int ret = 0;        bool start = false;        for (auto c : s) {            if (c == ' ') {                if (start) {                // a segment ended                    ++ret, start = false;                }            }            else {                if (!start) {               // a segment started                    start = true;                }            }        }        if (start) {                        // a segment ended at the end            ++ret;        }        return ret;    }};