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L15_3sum

admin 11月 13, 2020 0

题目描述

Given an array S of n integers, are there elements a, b, c in S such that a + b + c = 0? Find all unique triplets in the array which gives the sum of zero.

Note: The solution set must not contain duplicate triplets.

For example, given array S = [-1, 0, 1, 2, -1, -4],

A solution set is:
[
  [-1, 0, 1],
  [-1, -1, 2]
]

解题思路

首先将数组进行排序，排序后使用3个索引进行sum的判断

Go版本

import (
    "sort"
)

func (nums []int) [][]int {
    l := len(nums)
    r := [][]int{}
    sort.Ints(nums)
    for i:=0; i<l-2;i++  {
        j := i+1
        k := l-1

        for j<k {
            s := nums[i] + nums[j] + nums[k]

            if s>0{
                k--
            }else if s<0 {
                j++
            }else {
                row:=[]int{nums[i],nums[j], nums[k]}
                flag := true
                for _, v := range r{
                    if v[0]==row[0] &&v[1] == row[1] && v[2] == row[2] {
                        flag = false
                        break
                    }
                }
                if flag {
                    r = append(r,row)
                }
                j++
                k--
            }
        }
    }
    return r
}

Python版本

class Solution(object):
    def (self, nums):
        """
        :type nums: List[int]
        :rtype: List[List[int]]
        """
        r = []

        nums = sorted(nums)
        l = len(nums)

        for i in range(l):
            j = i + 1
            k = l - 1
            while j < k:
                s = nums[i] + nums[j] + nums[k]
                if s > 0:
                    k -= 1
                elif s < 0:
                    j += 1
                else:
                    t = [nums[i], nums[j], nums[k]]
                    if t not in r:
                        r.append(t)
                    j += 1
                    k -= 1
        return r