Question Definition
Given an array S of n integers, find three integers in S such that the sum is closest to a given number, target. Return the sum of the three integers. You may assume that each input would have exactly one solution.
For example, given array S = {-1 2 1 -4}, and target = 1.
The sum that is closest to the target is 2. (-1 + 2 + 1 = 2).
Java Solution
public int threeSumClosest(int[] nums, int target) {
int closest = nums[0] + nums[1] + nums[2];
int diff = Math.abs(closest - target);
Arrays.sort(nums);
for (int i = 0; i < nums.length - 2; ++i) {
int left = i + 1, right = nums.length - 1;
while (left < right) {
int sum = nums[i] + nums[left] + nums[right];
int newDiff = Math.abs(sum - target);
if (diff > newDiff) {
diff = newDiff;
closest = sum;
}
if (sum < target) ++left;
else --right;
}
}
return closest;
}
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