18. 四数之和

18. 四数之和

三个数只和 再次加一层for循环

package main
import (
    "fmt"
    "sort"
)
func fourSum(nums []int, target int) [][]int {
     var res [][]int
     sort.Ints(nums)
     for i:=0;i<len(nums)-3;i++{
         if i>0&&nums[i]==nums[i-1] {
            continue
         }
         for j:=i+1;j<len(nums)-2;j++{
            if j>i+1&&nums[j]==nums[j-1] {
                continue
            }
             l :=j+1
             r :=len(nums)-1
            for l<r {
                temp :=nums[i]+nums[j]+nums[l]+nums[r]
                if temp<target {
                    l++
                }else if temp>target {
                    r--
                }else {
                    res = append(res,[]int{nums[i],nums[j],nums[l],nums[r]})
                    l++
                    r--
                    for l>j+1&&nums[l]==nums[l-1] {
                        l++
                    }
                    for l<len(nums)-2&&nums[r]==nums[r+1]{
                        r--
                    }
                }
            }
        }
     }
     return res
}
func main() {
    fmt.Println(fourSum([]int{1, 0, -1, 0, -2, 2},0))
    fmt.Println(fourSum([]int{-3,-2,-1,0,0,1,2,3},0))
    fmt.Println(fourSum([]int{-1,0,-5,-2,-2,-4,0,1,-2},-9))
}