1248. Count Number of Nice Subarrays | LeetCode Solution
Given an array of integers nums
and an integer k
. A continuous subarray is called nice if there are k
odd numbers on it.
Return the number of nice sub-arrays.
Example 1:
Input: nums = [1,1,2,1,1], k = 3 Output: 2 Explanation: The only sub-arrays with 3 odd numbers are [1,1,2,1] and [1,2,1,1].
Example 2:
Input: nums = [2,4,6], k = 1 Output: 0 Explanation: There is no odd numbers in the array.
Example 3:
Input: nums = [2,2,2,1,2,2,1,2,2,2], k = 2 Output: 16
Constraints:
1 <= nums.length <= 50000
1 <= nums[i] <= 10^5
1 <= k <= nums.length
class Solution {
public:
int numberOfSubarrays(vector<int>& nums, int k) {
for(int i=0; i<nums.size(); i++){
if(nums[i]%2==0)nums[i]=0;
else nums[i]=1;
}
unordered_map<int,int>mymap;
int sum=0,ans=0;
mymap[sum]=1;
for(int i=0; i<nums.size(); i++){
sum+=nums[i];
auto it=mymap.find(sum-k);
if(it!=mymap.end())ans+=mymap[sum-k];
mymap[sum]++;
}
return ans;
}
};
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