import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
/**
* Three Sum
*
* 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≤ca \leq b \leq ca≤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)
*/
public class ThreeSum {
public List<List<Integer>> threeSum(int[] nums) {
List<List<Integer>> result = new ArrayList<List<Integer>>();
if (nums.length < 3) return result;
Arrays.sort(nums);
final int target = 0;
for (int i = 0; i < nums.length - 2; ++i) {
if (i > 0 && nums[i] == nums[i-1]) continue;
int j = i+1;
int k = nums.length-1;
while (j < k) {
if (nums[i] + nums[j] + nums[k] < target) {
++j;
while(nums[j] == nums[j-1] && j < k) ++j;
} else if(nums[i] + nums[j] + nums[k] > target) {
--k;
while(nums[k] == nums[k+1] && j < k) --k;
} else {
result.add(Arrays.asList(nums[i], nums[j], nums[k]));
++j;
--k;
while(nums[j] == nums[j-1] && j < k) ++j;
while(nums[k] == nums[k+1] && j < k) --k;
}
}
}
return result;
}
}
Three Sum(找出数组中,所有三个数字的组合,其和为给定值的情况)
最新推荐文章于 2023-12-11 15:07:59 发布