[LeetCode] 923. 3Sum With Multiplicity 三数之和的多种情况

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:

1. 3 <= A.length <= 3000
2. 0 <= A[i] <= 100
3. 0 <= target <= 300

Github 同步地址:

https://github.com/grandyang/leetcode/issues/923

类似题目：

参考资料：

https://leetcode.com/problems/3sum-with-multiplicity/

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[LeetCode] 923. 3Sum With Multiplicity 三数之和的多种情况

原文：https://www.cnblogs.com/grandyang/p/11818151.html