[LeetCode] Reverse Words in a String

题目:

Given an input string, reverse the string word by word.

For example,
Given s = "the sky is blue",
return "blue is sky the".

 

Clarification:

 

• What constitutes a word?
  A sequence of non-space characters constitutes a word.
• Could the input string contain leading or trailing spaces?
  Yes. However, your reversed string should not contain leading or trailing spaces.
• How about multiple spaces between two words?
  Reduce them to a single space in the reversed string.　　

这题刚看时觉得挺简单的，想了想发现这尼玛体力题啊，主要是处理连续空字符的需要注意一下.

public class Solution {

    public String reverseWords( String s ) {
        char[] chs = s.toCharArray();

        if( s.length() == 1 && s.charAt( 0 ) == ' ' )
            return new String();

        int start = 0;
        int empty = 0;
        int end0 = 0;
        for( int i = 0; i < s.length(); i++ ) {
            if( s.charAt( i ) != ' ' ) {
                start = i;
                break;
            } else {
                empty++;
            }
        }

        for( int i = s.length() - 1; i >= 0; i-- ) {
            if( s.charAt( i ) == ' ' ) {
                end0++;
            }else{
                break;
            }
        }
        if( empty == s.length() )
            return new String();
        s = new String( s.toCharArray(), start,s.length()-start-end0 );
        int l = 0;
        int r = s.length() - 1;
        chs = s.toCharArray();
        while( l < r ) {
            char temp = chs[ l ];
            chs[ l ] = chs[ r ];
            chs[ r ] = temp;
            l++;
            r--;
        }
        l = 0;
        r = s.length() - 1;
        int c = 0;
        for( int i = 0; i < r; i++ ) {
            if( chs[ i ] == ' ' && chs[ i + 1 ] == ' ' ) {
                for( int j = i; j < r; j++ ) {
                    chs[ j ] = chs[ j + 1 ];
                }
                r--;
                i--;
            }
        }
        while( l <= r ) {
            if( chs[ l ] == ' ' || l == r ) {
                int end = l - ( l == r ? 0 : 1 );
                while( c < end ) {
                    char temp = chs[ c ];
                    chs[ c ] = chs[ end ];
                    chs[ end ] = temp;
                    c++;
                    end--;
                }
                l++;
                c = l;
            } else {
                l++;
            }
        }

        String ret = new String( chs, 0, r + 1 );
        return ret;
    }

    public static void main( String[] args ) {
        Solution s = new Solution();
        System.out.println( s.reverseWords( "   a   b " ));
    }

}