# 16. 3Sum Closest

## 10 Jan 16. 3Sum Closest

Given an integer array `nums` of length `n` and an integer `target`, find three integers in `nums` such that the sum is closest to `target`.

Return the sum of the three integers.

You may assume that each input would have exactly one solution.

Example 1:

```Input: nums = [-1,2,1,-4], target = 1
Output: 2
Explanation: The sum that is closest to the target is 2. (-1 + 2 + 1 = 2).
```

Example 2:

```Input: nums = [0,0,0], target = 1
Output: 0
Explanation: The sum that is closest to the target is 0. (0 + 0 + 0 = 0).
```

Constraints:

• `3 <= nums.length <= 500`
• `-1000 <= nums[i] <= 1000`
• `-104 <= target <= 104`

```class Solution {
public:
int threeSumClosest(vector<int>& nums, int target) {
int closest = nums[0] + nums[1] + nums[2];
int diff = abs(closest - target);
sort(nums.begin(), nums.end());
for (int i = 0; i < nums.size() - 2; ++i) {
int left = i + 1, right = nums.size() - 1;
while (left < right) {
int sum = nums[i] + nums[left] + nums[right];
int newDiff = abs(sum - target);
if (diff > newDiff) {
diff = newDiff;
closest = sum;
}
if (sum < target) ++left;
else --right;
}
}
return closest;
}
};```

```class Solution {
public:
int threeSumClosest(vector<int>& nums, int target) {
int closest = nums[0] + nums[1] + nums[2];
int diff = abs(closest - target);
sort(nums.begin(), nums.end());
for (int i = 0; i < nums.size() - 2; ++i) {
if (nums[i] * 3 > target) return min(closest, nums[i] + nums[i + 1] + nums[i + 2]);
int left = i + 1, right = nums.size() - 1;
while (left < right) {
int sum = nums[i] + nums[left] + nums[right];
int newDiff = abs(sum - target);
if (diff > newDiff) {
diff = newDiff;
closest = sum;
}
if (sum < target) ++left;
else --right;
}
}
return closest;
}
};```
class Solution:
def threeSumClosest(self, nums: List[int], target: int) -> int:
closest = nums[0] + nums[1] + nums[2]
diff = abs(target – closest)
nums.sort()
n = len(nums)
print(nums)
for i in range(n-2):
left = i + 1
right = n – 1
print(“———————“)
print(i)
print(left)
print(right)
print(closest)
while left < right:
sum = nums[i] + nums[left] + nums[right]
new_diff = abs(target – sum)
# print(“****************”)
# print(nums[i])
# print(nums[left])
# print(nums[right])
# print(sum)
# print(new_diff)
if diff > new_diff:
diff = new_diff
closest = sum
# print(“\$\$\$\$”)
# print(closest)
if sum >= closest:
right -= 1
else:
left += 1
print(closest)
return closest