• leetcode46

        var permute = function(nums) {
            let res=[];
            let result=[];
            backtrack(nums,result,res);
            return res;
        };
        var backtrack=function(nums,result,res)
        {
            if(result.length==nums.length)//結(jié)束條件
            {
                res.push(result.slice());
                return;
            }
            for(let i=0;i<nums.length;i++)
            {

                if(result.includes(nums[i]))//排除選過的
                    continue;
                result.push(nums[i]);
                backtrack(nums,result,res);
                result.pop();
            }
        }

• leetcode47

        var permuteUnique = function(nums) {
            let res=[];
            let result=[];
            let used=[];
            nums.sort();
            permute(nums,result,used,res);
            return res;
        };
        var permute=function(nums,result,used,res)
        {
            if(nums.length==result.length)
            {
                res.push(result.slice());
                return;
            }
            for(let i=0;i<nums.length;i++)
            {
                if(used[i]) continue;
                if(i>0 && nums[i] == nums[i-1] && used[i-1]) break;
                result.push(nums[i]);
                used[i]=true;
                permute(nums,result,used,res);
                result.pop();
                used[i]=false;
                
            }
        }