@author stormma
@date 2017/11/03
生命不息,奮鬥不止
題目
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).
思路分析
其實就是3sum的翻版,只要掌握了上一個題目的做法,這個理所當然可以套上一套題目的做法。
先確定1一個數,two pointer去查找,查找之後和target比較,比較上一次(sum - target) 和這次的(sum - target)的差值(sum表示我們查找的三個數的和)
代碼實現
class Solution {
public int threeSumClosest(int[] nums, int target) {
if (nums.length == 1) {
return nums[0];
}
Arrays.sort(nums);
int result = Integer.MAX_VALUE >> 1;
for (int i = 0; i < nums.length - 2; i++) {
int low = i + 1, high = nums.length - 1;
int goal = target - nums[i];
while (low < high) {
if (goal == nums[low] + nums[high]) {
return target;
}
result = Math.abs(goal - nums[low] - nums[high]) > Math.abs(result - target) ? result: nums[i] + nums[low] + nums[high];
if (goal > nums[low] + nums[high]) {
low++;
} else {
high--;
}
}
}
return result;
}
}