Create 0018-4Sum.go solution

go/0018-4Sum.go

@@ -0,0 +1,45 @@
+func fourSum(nums []int, target int) [][]int {
+ if len(nums) < 4 {
+ return [][]int{}
+ }
+
+ sort.Ints(nums)
+
+ result := make([][]int, 0)
+
+ for i, ival := range nums {
+ if i != 0 && nums[i] == nums[i - 1] {
+ continue
+ }
+
+ for j := i + 1; j < len(nums) - 1; j++ {
+ if j != i+1 && nums[j] == nums[j-1] {
+ continue
+ }
+
+ jval := nums[j]
+
+ for l, r := j+1, len(nums) - 1; l < r; {
+ lval, rval := nums[l], nums[r]
+
+ sum := ival + jval + lval + rval
+ switch {
+ case sum < target:
+ l++
+ case sum > target:
+ r--
+ default:
+ result = append(result, []int{ival, jval, lval, rval})
+ for ; l < r && nums[l] == nums[l+1]; l++ {
+ }
+ for ; l < r && nums[r] == nums[r-1]; r-- {
+ }
+ l++
+ r--
+ }
+ }
+ }
+ }
+
+ return result
+}