题解 | #集合的所有子集(一)#

 * 
 * @param A int整型一维数组 
 * @return int整型二维数组
 */
function subsets( A ) {
    // write code here
    if(A.length == 0)    return [];
    A.sort(function(a,b){return a- b;})
    let res = [],tmp = [];
    res.push([]);
    for(let i = 1;i <= A.length;i++){
        sub(A,res,tmp,0,i);
    }
    return res;
}
function sub( A,res,tmp,start,num ){
    if(tmp.length === num){
        res.push(tmp.slice());
        return;
    }
    for(let i = start;i < A.length;i++){
        tmp.push(A[i]);
        sub(A,res,tmp,i + 1,num)
        tmp.pop();
    }
}
module.exports = {
    subsets : subsets
};