DAY41|343. 整数拆分 96.不同的二叉搜索树

343. 整数拆分 

class Solution {
public:
    int integerBreak(int n) {
        //确定dp数组（dp table）以及下标的含义
        vector dp(n+1);
        dp[0] = 0;
        dp[1] = 1;
        dp[2] = 1;
        //确定递推公式
        for(int i = 3;i <= n;i++){
            for (int j = 1; j < i - 1; j++){
                dp[i] = max({dp[i], (i - j) * j, dp[i - j] * j});
            }
            
        }
    return dp[n];
    }
};

96.不同的二叉搜索树

class Solution {
public:
    int numTrees(int n) {
        vector dp(n + 1);
        dp[0] = 1;
        for (int i = 1; i <= n; i++) {
            for (int j = 1; j <= i; j++) {
                dp[i] += dp[j - 1] * dp[i - j];
            }
        }
        return dp[n];
    }
};