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ThreeSum.java
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51 lines (46 loc) · 1.63 KB
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package nSum;
import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.Arrays;
public class ThreeSum {
// 规定遍历的起点，防止出现重复计算
// 在这里假设已经排号序了，从小到大
private ArrayList<ArrayList<Integer>> twoSum(int[] nums, int target, int start) {
ArrayList<ArrayList<Integer>> res = new ArrayList<ArrayList<Integer>>();
int low = start;
int high = nums.length-1;
while(low<high) {
if(nums[low]+nums[high]<target) {
low++;
}else if(nums[low]+nums[high]>target) {
high--;
}else {
ArrayList<Integer> tempList = new ArrayList<Integer>();
tempList.add(nums[low]);
tempList.add(nums[high]);
res.add(tempList);
int temp = nums[low];
low++;
while(temp==nums[low] && low<high) {
low++;
}
}
}
return res;
}
ArrayList<ArrayList<Integer>> threeSum(int[] nums, int target){
Arrays.sort(nums);
ArrayList<ArrayList<Integer>> res= new ArrayList<ArrayList<Integer>>();
for(int i=0;i<nums.length;i++) {
ArrayList<ArrayList<Integer>> part = twoSum(nums, target-nums[i], i+1);
if(part.size()>0) {
for(int j=0;i<part.size();i++){
ArrayList<Integer> temp = new ArrayList<Integer>();
part.get(j).add(0, nums[i]);
res.add(part.get(j));
}
}
}
return res;
}
}