【LeetCode从零单排】No15 3Sum

称号

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:

Elements in a triplet (a,b,c) must be in non-descending order. (ie, a ≤ b ≤ c)
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)

代码

public class Solution {
public List<List<Integer>> threeSum(int[] num) {
Arrays.sort(num);
int a,b,c;
HashSet<List<Integer>> hs=new HashSet();
for(int i=0;i<=num.length-3;i++){
a=num[i];
for(int m=i+1,n=num.length-1; m<n;){
b=num[m];
c=num
;
if(-a==(b+c)){
List<Integer> ls=new ArrayList<Integer>();
ls.add(a);
ls.add(b);
ls.add(c);
hs.add(ls);
n--;
m++;
}
else if(-a>(b+c)){
m++;
}
else{
n--;
}
}
}
List<List<Integer>> result=new ArrayList(hs);
return result;
}

}

代码下载：https://github.com/jimenbian/GarvinLeetCode
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