技術標籤：leetcodepython演算法

Leetcode 440 字典序的第k小數字

def findKthNumber(self, n: int, k: int) -> int:
        #十叉樹求解
        def cal_steps(n,n1,n2):
            step=0
            while n1<=n:
                step+=min(n2,n+1)-n1
                n1*=10
                n2*=
 
10
            return step
        cur=1
        k-=1
        while k>0:
            steps=cal_steps(n,cur,cur+1)
            if steps<=k:
                k-=steps
                cur+=1
            else:
                k-=1
                cur*=10
        return cur