首页 > 其他 > 详细

LC 992. Subarrays with K Different Integers

时间:2019-02-10 23:07:13      阅读:371      评论:0      收藏:0      [点我收藏+]

Given an array A of positive integers, call a (contiguous, not necessarily distinct) subarray of A good if the number of different integers in that subarray is exactly K.

(For example, [1,2,3,1,2] has 3 different integers: 12, and 3.)

Return the number of good subarrays of A.

 

Example 1:

Input: A = [1,2,1,2,3], K = 2
Output: 7
Explanation: Subarrays formed with exactly 2 different integers: [1,2], [2,1], [1,2], [2,3], [1,2,1], [2,1,2], [1,2,1,2].

Example 2:

Input: A = [1,2,1,3,4], K = 3
Output: 3
Explanation: Subarrays formed with exactly 3 different integers: [1,2,1,3], [2,1,3], [1,3,4].

 

Note:

  1. 1 <= A.length <= 20000
  2. 1 <= A[i] <= A.length
  3. 1 <= K <= A.length

 

 

Runtime: 128 ms, faster than 100.00% of C++ online submissions for Subarrays with K Different Integers.
Memory Usage: 25 MB, less than 100.00% of C++ online submissions for Subarrays with K Different Integers.

 

class Solution {
public:
  int subarraysWithKDistinct(vector<int>& A, int K) {
    return atMostK(A, K) - atMostK(A,K-1);
  }
  int atMostK(vector<int>& A, int K) {
    int i = 0,res = 0;
    unordered_map<int,int> mp;
    for(int j=0; j<A.size(); j++) {
      if(!mp[A[j]]++) K--;
      while(K<0){
        if(!--mp[A[i]]) K++;
        i++;
      }   
      res += j - i + 1;
    }   
    return res;
  }
};

 

LC 992. Subarrays with K Different Integers

原文:https://www.cnblogs.com/ethanhong/p/10360555.html

(0)
(0)
   
举报
评论 一句话评论(0
关于我们 - 联系我们 - 留言反馈 - 联系我们:wmxa8@hotmail.com
© 2014 bubuko.com 版权所有
打开技术之扣,分享程序人生!