LengthofLastWord

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problem

Given a string s consists of upper/lower-case alphabets and empty space characters ' ', return the length of last word in the string.

If the last word does not exist, return 0.

Note: A word is defined as a character sequence consists of non-space characters only.

Example:

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Input: "Hello World"
Output: 5

key

该方法调用了java的String.split(regex)所以在复杂度上回很高，大概仅仅beat了6%的玩家，但解决很快，正确的算法思维就倒序遍历，最后开始查往前，最后一个非空格查到空格结束

solution

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//7ms
public int lengthOfLastWord(String s) {
		if(s.length()<=0)return 0;
		String[] tmp = s.split("\\s");
		int lastIndex = tmp.length-1;
		if(lastIndex<0) {
			return 0;
		}else {
			return tmp[lastIndex].length();
		}
		
	}

perfect

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class Solution {
    public int lengthOfLastWord(String s) {
        int n = s.length() - 1;
        int length = 0;
        for(int i = n; i >= 0; i--) {
            if(length == 0) {
                if(s.charAt(i) == ' ') {
                    continue;
                }else {
                    length++;
                }
            }else {
                if(s.charAt(i) == ' ') {
                    break;
                }
                else {
                    length++;
                }
            }
        }
        return length;
    }
}