[LeetCode] 1023. Camelcase Matching

A query word matches a given pattern if we can insert lowercase letters to the pattern word so that it equals the query. (We may insert each character at any position, and may insert 0 characters.)

Given a list of queries, and a pattern, return an answer list of booleans, where answer[i] is true if and only if queries[i] matches the pattern.

Example 1:

Input: queries = ["FooBar","FooBarTest","FootBall","FrameBuffer","ForceFeedBack"], pattern = "FB"
Output: [true,false,true,true,false]
Explanation: 
"FooBar" can be generated like this "F" + "oo" + "B" + "ar".
"FootBall" can be generated like this "F" + "oot" + "B" + "all".
"FrameBuffer" can be generated like this "F" + "rame" + "B" + "uffer".

Example 2:

Input: queries = ["FooBar","FooBarTest","FootBall","FrameBuffer","ForceFeedBack"], pattern = "FoBa"
Output: [true,false,true,false,false]
Explanation: 
"FooBar" can be generated like this "Fo" + "o" + "Ba" + "r".
"FootBall" can be generated like this "Fo" + "ot" + "Ba" + "ll".

Example 3:

Input: queries = ["FooBar","FooBarTest","FootBall","FrameBuffer","ForceFeedBack"], pattern = "FoBaT"
Output: [false,true,false,false,false]
Explanation: 
"FooBarTest" can be generated like this "Fo" + "o" + "Ba" + "r" + "T" + "est".

Note:

1. 1 <= queries.length <= 100
2. 1 <= queries[i].length <= 100
3. 1 <= pattern.length <= 100
4. All strings consists only of lower and upper case English letters.

驼峰式匹配。

如果我们可以将小写字母插入模式串 pattern 得到待查询项 query，那么待查询项与给定模式串匹配。（我们可以在任何位置插入每个字符，也可以插入 0 个字符。）

给定待查询列表 queries，和模式串 pattern，返回由布尔值组成的答案列表 answer。只有在待查项 queries[i] 与模式串 pattern 匹配时， answer[i] 才为 true，否则为 false。

来源：力扣（LeetCode）
链接：https://leetcode-cn.com/problems/camelcase-matching
著作权归领扣网络所有。商业转载请联系官方授权，非商业转载请注明出处。

思路是双指针，类似找字符串子序列的感觉。对于 input 数组里面的每一个单词 q，我们需要跟 pattern 进行对照。对照的方式是双指针。这里我使用了一个 flag 来记录到底是 true 还是 false。false的条件请参见代码注释。

时间O(mn) - m个单词，平均长度n

空间O(m) - output list

Java实现

class Solution {
    public List<Boolean> camelMatch(String[] queries, String pattern) {
        List<Boolean> res = new ArrayList<>();
        for (String q : queries) {
            int i = 0;
            int j = 0;
            boolean flag = true;
            while (i < q.length() && j < pattern.length()) {
                // 当前单词中有大写字母但是pattern里没有
                if (q.charAt(i) >= 'A' && q.charAt(i) <= 'Z') {
                    if (q.charAt(i) != pattern.charAt(j)) {
                        flag = false;
                    }
                }
                if (q.charAt(i) == pattern.charAt(j)) {
                    j++;
                }
                i++;
            }
            // pattern没走完，false
            if (j != pattern.length()) {
                flag = false;
            }
            // 当前单词没走完，有大写字母，false
            while (i < q.length()) {
                if (q.charAt(i) >= 'A' && q.charAt(i) <= 'Z') {
                    flag = false;
                    break;
                }
                i++;
            }
            res.add(flag);
        }
        return res;
    }
}

LeetCode 题目总结