Leetcode-673 (Number of Longest Increasing Subsequence)最长递增子序列的个数

#define _for(i,a,b) for(int i = (a);i < (b);i ++)
class Solution
{
    public:
        int findNumberOfLIS(vector<int>& nums)
        {
            int sz = nums.size();
            vector<pair<int,int>> dp (sz,{1,1});//LISlen times
            
            int LISlen = 1;
            for(int i = 1;i < sz;i ++)
            {
                for(int j = 0;j < i;j ++)
                {
                    if(nums[i]>nums[j]&&dp[j].first+1>dp[i].first)
                    {
                        
                        dp[i].first = dp[j].first+1;
                        dp[i].second = dp[j].second;
                        LISlen = max(LISlen,dp[i].first);
                    }
                    else if(nums[i]>nums[j]&&dp[j].first+1==dp[i].first)
                    {
                        dp[i].second += dp[j].second;
                    }
                }
            }
            
            int rnt = 0;
            _for(i,0,sz)
                if(dp[i].first==LISlen)
                    rnt += dp[i].second;
            return rnt;
        }
};