最长递增子序列的个数

Leetcode题目链接

描述

详见中文题目链接。

解答

class Solution {
public:
    int findNumberOfLIS(vector<int>& nums) {
        int n = nums.size();
        vector<int> dp(n, 1), count(n, 1);

        for (int i = 1; i < n; i++) {
            for (int j = 0; j < i; j++) {
                if (nums[i] > nums[j]) {
                    if (dp[j] + 1 > dp[i]) {
                        dp[i] = dp[j] + 1;
                        count[i] = count[j];
                    } else if (dp[j] + 1 == dp[i]) {
                        count[i] += count[j];
                    }
                }
            }
        }

        int maxVal = *max_element(dp.begin(), dp.end());
        int res = 0;
        for (int i = 0; i < n; i++) {
            if (dp[i] == maxVal) res += count[i];
        }
        return res;
    }
};