Leetcode #186. Reverse Words in a String II

[yokostan]

class Solution {
    public void reverseWords(char[] str) {
        if (str == null || str.length == 0) return ;
        swap(str, 0, str.length - 1);

        int start = 0;
        while (start < str.length) {
            int end = start;
            while (end < str.length && str[end] != ' ') {
                end++;
            }
            swap(str, start, end - 1);
            start = end + 1;
        }
    }

    private void swap(char[] str, int i, int j) {
        if (i == j) return ;
        while (i < j && j < str.length) {
            char tmp = str[i];
            str[i] = str[j];
            str[j] = tmp;
            i++;
            j--;
        }
    }
}