[LeetCode] 524. Longest Word in Dictionary through Deleting

Given a string and a string dictionary, find the longest string in the dictionary that can be formed by deleting some characters of the given string. If there are more than one possible results, return the longest word with the smallest lexicographical order. If there is no possible result, return the empty string.

Example 1:

Input:
s = "abpcplea", d = ["ale","apple","monkey","plea"]

Output: 
"apple"

Example 2:

Input:
s = "abpcplea", d = ["a","b","c"]

Output: 
"a"

Note:

1. All the strings in the input will only contain lower-case letters.
2. The size of the dictionary won't exceed 1,000.
3. The length of all the strings in the input won't exceed 1,000.

题意：找出d中的最长的s的子串

从d中一个一个判断就行了。。(其实可以维护一个长度标记，小于这个长度就不判断了，可以优化一些。由于当时写的着急，这里就不写了)

class Solution {
    public String findLongestWord(String s, List<String> d) {
        TreeSet<String> set = new TreeSet<String>((s1, s2)-> {
            if (s1.length() < s2.length())
                return 1;
            if (s1.length() > s2.length())
                return -1;
            if (s1.compareTo(s2) > 0)
                return 1;
            if (s1.compareTo(s2) < 0)
                return -1;
            return 0;
        });
        for (String str : d) {
            if (isVal(s, str))
                set.add(str);
        }
        if (set.size() == 0)
            return "";
        return set.first();
    }
    public boolean isVal(String superStr, String subStr) {
        int i = 0;
        int j = 0;
        while (i < superStr.length()) {
            if (superStr.charAt(i) == subStr.charAt(j)) {
                i ++;
                j ++;
                if (j == subStr.length())
                    return true;
            }
            else 
                i ++;
        }
        return false;
    }
}