Practice 4Sum II
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4Sum II
Given four integer arrays nums1, nums2, nums3 and nums4, each of length n, count the index tuples (i, j, k, l) for which nums1[i] + nums2[j] + nums3[k] + nums4[l] equals zero. Each index ranges from 0 through n - 1. Choose one element from each array; different index tuples count separately even when their selected values are equal.
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Understanding the 4Sum II Problem
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Problem Statement
Given four integer arrays nums1, nums2, nums3 and nums4, each of length n, count the index tuples (i, j, k, l) for which nums1[i] + nums2[j] + nums3[k] + nums4[l] equals zero. Each index ranges from 0 through n - 1. Choose one element from each array; different index tuples count separately even when their selected values are equal.
Source: 4Sum II on LeetCode. Use the original task for its coding environment and submissions.
4Sum II
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Examples
# Example 1
nums1 = [1,2], nums2 = [-2,-1], nums3 = [-1,2], nums4 = [0,2]
2
# Example 2
nums1 = [0], nums2 = [0], nums3 = [0], nums4 = [0]
1
Constraints
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