Algorithm
Problem Name: 454. 4Sum II
Given four integer arrays nums1, nums2, nums3, and nums4 all of length n, return the number of tuples (i, j, k, l) such that:
0 <= i, j, k, l < nnums1[i] + nums2[j] + nums3[k] + nums4[l] == 0
Example 1:
Input: nums1 = [1,2], nums2 = [-2,-1], nums3 = [-1,2], nums4 = [0,2] Output: 2 Explanation: The two tuples are: 1. (0, 0, 0, 1) -> nums1[0] + nums2[0] + nums3[0] + nums4[1] = 1 + (-2) + (-1) + 2 = 0 2. (1, 1, 0, 0) -> nums1[1] + nums2[1] + nums3[0] + nums4[0] = 2 + (-1) + (-1) + 0 = 0
Example 2:
Input: nums1 = [0], nums2 = [0], nums3 = [0], nums4 = [0] Output: 1
Constraints:
n == nums1.lengthn == nums2.lengthn == nums3.lengthn == nums4.length1 <= n <= 200-228 <= nums1[i], nums2[i], nums3[i], nums4[i] <= 228
Code Examples
#1 Code Example with Java Programming
Code -
Java Programming
class Solution {
public int fourSumCount(int[] A, int[] B, int[] C, int[] D) {
Map map = new HashMap<>();
for (int i=0; i Input
nums1 = [1,2], nums2 = [-2,-1], nums3 = [-1,2], nums4 = [0,2]
Output
2
#2 Code Example with Javascript Programming
Code -
Javascript Programming
const fourSumCount = function(A, B, C, D) {
const map = new Map()
let res = 0
for (let i = 0, clen = C.length; i < clen; i++) {
for (let j = 0, dlen = D.length; j < dlen; j++) {
map.set(
C[i] + D[j],
typeof map.get(C[i] + D[j]) == 'undefined'
? 1
: map.get(C[i] + D[j]) + 1
)
}
}
for (let i = 0, alen = A.length; i < alen; i++) {
for (let j = 0, blen = B.length; j < blen; j++) {
res +=
typeof map.get((A[i] + B[j]) * -1) == 'undefined'
? 0
: map.get((A[i] + B[j]) * -1)
}
}
return res
}
Input
nums1 = [1,2], nums2 = [-2,-1], nums3 = [-1,2], nums4 = [0,2]
Output
2
#3 Code Example with Python Programming
Code -
Python Programming
class Solution:
def fourSumCount(self, A: List[int], B: List[int], C: List[int], D: List[int]) -> int:
ab = collections.Counter([a + b for a in A for b in B])
return sum(-c - d in ab and ab[-c-d] for c in C for d in D)
Input
nums1 = [0], nums2 = [0], nums3 = [0], nums4 = [0]
Output
1
#4 Code Example with C# Programming
Code -
C# Programming
start coding...