leetcode 186: Reverse Words in a String II

Total Accepted: 421
Total Submissions: 1404

Given an input string, reverse the string word by word. A word is defined as a sequence of non-space characters.

The input string does not contain leading or trailing spaces and the words are always separated by a single space.

For example,

Given s = "the sky is blue",

return "blue is sky the".

Could you do it in-place without allocating extra space?

[思路]

反转整个字符串, 再反转每个单词即可

[注意]

None

[DODE]

public class Solution {
    //the sky is blue
    public void reverseWords(char[] s) {
        //input check
        if(s.length<=1) return;

        swap(s, 0, s.length-1);

        int i=0, j=1;

        while(j<s.length) {
            while(j<s.length && s[j]!=' ') {
                ++j;
            }
            swap(s, i, j-1);
            i = j+1;
            j = i+1;
        }

    }

    private void swap(char[] s, int i, int j) {
        while(i<j) {
            char temp = s[i];
            s[i] = s[j];
            s[j] = temp;
            ++i;
            --j;
        }
    }
}