Given an integer array A
, and an integer target
, return the number of tuples i, j, k
such that i < j < k
and A[i] + A[j] + A[k] == target
.
As the answer can be very large, return it modulo 10^9 + 7
.
Example 1:
Input: A = [1,1,2,2,3,3,4,4,5,5], target = 8 Output: 20 Explanation: Enumerating by the values (A[i], A[j], A[k]): (1, 2, 5) occurs 8 times; (1, 3, 4) occurs 8 times; (2, 2, 4) occurs 2 times; (2, 3, 3) occurs 2 times.
Example 2:
Input: A = [1,1,2,2,2,2], target = 5 Output: 12 Explanation: A[i] = 1, A[j] = A[k] = 2 occurs 12 times: We choose one 1 from [1,1] in 2 ways, and two 2s from [2,2,2,2] in 6 ways.
Note:
3 <= A.length <= 3000
0 <= A[i] <= 100
0 <= target <= 300
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Related Topics:
Two Pointers