例如,給定數組 nums = [-1,2,1,-4], 和 target = 1.
與 target 最接近的三個數的和爲 2. (-1 + 2 + 1 = 2).
來源:力扣(LeetCode)
鏈接:https://leetcode-cn.com/problems/3sum-closest
/**
* @param {number[]} nums
* @param {number} target
* @return {number}
*/
var threeSumClosest = function (nums, target) {
const len = nums.length;
if (len < 3) {
return null;
}
nums.sort((a, b) => a - b); // 升序排序
console.log(nums)
// 結果,比存儲 sum 方便,下面對比時不用再用 target - sum 對比
let res = target - (nums[0] + nums[1] + nums[2]);
for (let i = 0; i < len - 2; i++) {
// 左指針爲 i+1,右指針爲 nums.length - 1
let left = i + 1,
right = len - 1;
while (left < right) {
const sum = nums[i] + nums[left] + nums[right];
if (sum === target) {
return sum;
} else if (sum < target) {
// sum < target 時,left++
left++;
} else {
// sum > target時,right--
right--;
}
// 存儲與 target 最近的值
if (Math.abs(target - sum ) < Math.abs(res)) {
res = target - sum;
}
}
}
return target - res;
};