Class Solution
- java.lang.Object
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- g0601_0700.s0629_k_inverse_pairs_array.Solution
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public class Solution extends Object
629 - K Inverse Pairs Array.Hard
For an integer array
nums
, an inverse pair is a pair of integers[i, j]
where0 <= i < j < nums.length
andnums[i] > nums[j]
.Given two integers n and k, return the number of different arrays consist of numbers from
1
ton
such that there are exactlyk
inverse pairs. Since the answer can be huge, return it modulo109 + 7
.Example 1:
Input: n = 3, k = 0
Output: 1
Explanation: Only the array [1,2,3] which consists of numbers from 1 to 3 has exactly 0 inverse pairs.
Example 2:
Input: n = 3, k = 1
Output: 2
Explanation: The array [1,3,2] and [2,1,3] have exactly 1 inverse pair.
Constraints:
1 <= n <= 1000
0 <= k <= 1000
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Constructor Summary
Constructors Constructor Description Solution()
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description int
kInversePairs(int n, int k)
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