LeetCode 第一题剪彩自己的leetCode之路

Reverse Words in a String

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

For example,

Given s = "the sky is blue",

return "blue is sky the".

click to show clarification.

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.

public class Solution {
    public String reverseWords(String s) {
		 // 判断 ""
		if(s.length()==0) return "";
		// 判断" "
		if(s.length()==1 && s.charAt(0)==' ')return "";

		int num = 0;
		boolean flag = false;
		// 得到字符串中单词的个数
		for(int i=0; i < s.length(); i++){
			if(s.charAt(i)!=' '){
				flag = true;
			}else{
				if(flag){
					num++;
					flag = false;
				}
			}
		}
		String str[] = new String[num+1];
		int len=0;

		// 分离出单词
		String tempStr = "";
		flag  = false;
		for(int i=0; i < s.length(); i++){
			if(s.charAt(i)!=' '){
				tempStr += s.charAt(i);
				flag = true;
			}else{
				if(flag){
					flag = false;
					str[len++] = tempStr;
					tempStr = "";
				}
			}
		}
		str[len] = tempStr;

		// 对单词进行组合，在单词之间加上空格
		String resu = "";
		for(int i=str.length-1; i>=0; i--){
			resu+=str[i];
			if(i!=0)
				resu += " ";
		}
		// 判断结果为""的情况
		if(resu.length()==0) return "";

		// 去除前导零和后置零
		int count=0;
		while(resu.charAt(count)==' '){
			resu = resu.substring(count+1);
		}
		count = resu.length()-1;
		while(resu.charAt(count)== ' '){
			resu = resu.substring(0, count);
			count--;
		}
		return resu;
	}
}

LeetCode 第一题剪彩自己的leetCode之路