题解 | #数组中相加和为0的三元组#

 * 
 * @param num int整型一维数组 
 * @return int整型二维数组
 */
function threeSum( num ) {
    // write code here
    let len = num.length;
    if(len < 3)    return [];
    num.sort(function(a,b){return a - b});    //    排序
    let res = [];
    let target,left,right,sum;
    for(let i = 0;i < len - 2;i++){
        while(i > 0 && num[i] === num[i - 1])    i++;    //去重
        target = -num[i];
        left = i + 1;
        right = len - 1;
        while(left < right){
            sum = num[left] + num[right];
            if(sum === target){
                res.push([num[i],num[left],num[right]]);
                while(left < right && num[left] === num[left + 1])    left++;    //去重
                left++;
            }else{
                sum > target ? right-- : left++;
            }
        }
    }
    
    return res;
}
module.exports = {
    threeSum : threeSum
};