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).
解題思路就是枚舉出所有組合苇侵，然后不斷更新優(yōu)化bestSum
public class Solution {
/**
* @param numbers: Give an array numbers of n integer
* @param target : An integer
* @return : return the sum of the three integers, the sum closest target.
*/
public int threeSumClosest(int[] numbers, int target) {
// write your code here
if (numbers == null || numbers.length < 3) {
return -1;
}
Arrays.sort(numbers);
int bestSum = numbers[0] + numbers[1] + numbers[2];
for (int i = 0; i < numbers.length; i++) {
int start = i + 1, end = numbers.length - 1;
while (start < end) {
int sum = numbers[i] + numbers[start] + numbers[end];
if (Math.abs(target - sum) < Math.abs(target - bestSum)) {
bestSum = sum;
}
if (sum < target) {
start++;
} else {
end--;
}
}
}
return bestSum;
}
}
