Created
June 29, 2022 00:55
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still it doesn't prevent the edge case when nums = [1,1,1,1], target = 4
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class Solution { | |
private List<List<Integer>> result = new ArrayList(); | |
public List<List<Integer>> fourSum(int[] nums, int target) { | |
Arrays.sort(nums); | |
List<Integer> previousNum = new ArrayList(); | |
kSum(previousNum, nums, 4, 0, target); | |
return result; | |
} | |
public void kSum(List<Integer> previousNum, int[] nums, int k, int start, int target) { | |
if(k > 2) { | |
for(int i = start; i < nums.length-k+1; i++){ | |
if(i > start && nums[i] == nums[i-1]){ | |
continue; | |
} | |
previousNum.add(nums[i]); | |
kSum(previousNum, nums, k-1, i+1, target - nums[i]); | |
previousNum.remove(previousNum.size()-1); | |
} | |
} else { | |
int left = start; | |
int right = nums.length -1; | |
while(left < right){ | |
int sum = nums[left] + nums[right]; | |
if(sum < target){ | |
left++; | |
} else if(sum > target){ | |
right--; | |
} else { | |
List<Integer> subset = new ArrayList(); | |
subset.addAll(previousNum); | |
subset.add(nums[left]); | |
subset.add(nums[right]); | |
result.add(subset); | |
left++; | |
while(left < right && nums[left] == nums[left-1] ){ | |
left++; | |
} | |
} | |
} | |
} | |
} | |
public int sumList(List<Integer> previousNum){ | |
int sum = 0; | |
if(previousNum != null && !previousNum.isEmpty()){ | |
for(int i = 0; i < previousNum.size(); i++){ | |
sum += previousNum.get(i); | |
} | |
} | |
return sum; | |
} | |
} | |
// -2,-1,0,0,1,2 |
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