OA里的题目求帮忙

大家好 我遇到这两道题目。我感觉难，做不来，求大家帮助讲解思路! 如果肯把代码也写出来更谢谢。 3. determine if strings are close

Write a function to determine if two strings are close. For two strings to be considered close, they must be same after doing the either or both of following steps for any number of times: 1) swap any two characters within one string 2) change all occurrences of one character in one string into another character that exists in the same string e.g. "aaaabb" can be converted into "bbbbaa"


4. process queries
Given an integer array (int[] a) and a 2D array(int[][] queries). The 2D array represents a set of queries. You need to process the queries to find the number of occurrence of a specific number in array a between index i and j(inclusive). Each query is formatted in the following way: Each query has size 3(query.length=3, 0<=i<queries.length) The first element is the lower index i. The second element is the higher index j and the third element is the number you are searching for. Return the sum of numbers of occurrences you get from processing all the queries. (Brute force solution will not be efficient enough to pass all test cases).

第一题，统计每个字符串各个字符的frequency，然后sort，如果sort后一样说明可以change.
第二题我个人认为用前缀和，用一个map，key是数字，value是一个数组arr，arr[i]表示0-i有多少个，那么query[i, j, num]就是map.get(num)[j]-map.get(num)[i]

YanJuefei 发表于 2019-10-23 09:47
第一题，统计每个字符串各个字符的frequency，然后sort，如果sort后一样说明可以change.
第二题我个人认为 ...

请问第一题怎么sort

1) frequency排序, 分别得到一个. a的freq总<=b即可

2) 每个数造一个prefix 数组即可

拿汉语解释清楚，我帮你想

F119PW100 发表于 2019-10-31 23:15
拿汉语解释清楚，我帮你想

不必了，谢谢了