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_15_3Sum.java
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_15_3Sum.java
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package leetcode;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
/**
* Created by pingcai on 17-4-27.
*/
public class _15_3Sum {
public static void main(String[] args) {
int[] a = new int[]{-1, 0, 1, 2, -1, -4};
System.out.println(new _15_3Sum().threeSum(a));
}
public List<List<Integer>> threeSum(int[] nums) {
List<List<Integer>> list = new ArrayList<>();
if (nums == null || nums.length < 3) {
return list;
}
int i = 0;
Arrays.sort(nums);
while (i < nums.length - 2 && nums[i] <= 0) {
if (i > 0 && nums[i] == nums[i - 1]) {
i++;
continue;
}
int j = i + 1;
int k = nums.length - 1;
while (j < k) {
int x = nums[i] + nums[j] + nums[k];
if (x == 0) {
list.add(Arrays.asList(nums[i], nums[j], nums[k]));
j++;
k--;
while (j < k && nums[j] == nums[j - 1]) j++;
while (j < k && nums[k] == nums[k + 1]) k--;
} else if (x < 0) {
j++;
} else {
k--;
}
}
i++;
}
return list;
}
}