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ThreeSumTripletSmallerThanTarget.java
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ThreeSumTripletSmallerThanTarget.java
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package Leetcode;
import java.util.Arrays;
/**
* @author kalpak
*
* Given an array of n integers nums and an integer target,
* find the number of index triplets i, j, k with 0 <= i < j < k < n that satisfy the condition nums[i] + nums[j] + nums[k] < target.
*
* Follow up: Could you solve it in O(n2) runtime?
*
* Example 1:
* Input: nums = [-2,0,1,3], target = 2
* Output: 2
* Explanation: Because there are two triplets which sums are less than 2:
* [-2,0,1]
* [-2,0,3]
*
* Example 2:
* Input: nums = [], target = 0
* Output: 0
*
* Example 3:
* Input: nums = [0], target = 0
* Output: 0
*
* Constraints:
*
* n == nums.length
* 0 <= n <= 300
* -100 <= nums[i] <= 100
* -100 <= target <= 100
*/
public class ThreeSumTripletSmallerThanTarget {
public static int threeSumSmaller(int[] nums, int target) {
Arrays.sort(nums);
int result = 0;
for(int i = 0; i < nums.length - 2; i++) {
int left = i+1;
int right = nums.length - 1;
while(left < right) {
if (nums[left] + nums[right] + nums[i] < target) {
result += right - left;
left++;
} else {
right--;
}
}
}
return result;
}
public static void main(String[] args) {
int[] nums = new int[]{-2,0,1,3};
System.out.println(threeSumSmaller(nums, 2));
}
}