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# 259 3Sum Smaller

### Problem:

Given an array of n integers nums and a 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.

For example, given nums = \[-2, 0, 1, 3], and target = 2.

Return 2. Because there are two triplets which sums are less than 2:

```
[-2, 0, 1]
[-2, 0, 3]
```

Follow up: Could you solve it in O(n2) runtime?

### Solutions:

```java
public class Solution {
    public int threeSumSmaller(int[] nums, int target) {
        int count = 0;
        Arrays.sort(nums);
        for (int i = 0; i < nums.length - 2; i ++) {
            int left = i + 1, right = nums.length - 1;
            while (left < right) {
                if (nums[i] + nums[left] + nums[right] < target) {
                    count += right - left;
                    left ++;
                }
                else {
                    right --;
                }
            }
        }
        return count;
    }
}
```