Leetcode 440. 字典序的第K小数字

题目

Leetcode 440. 字典序的第K小数字

代码（10.2 首刷看解析）

首刷用优先队列超时了

字典序

class Solution {
public:
    int findKthNumber(int n, int k) {
        int curr = 1;
        k--;
        while(k) {
            int steps = getSteps(curr, n);
            if(steps <= k) {
                k -= steps;
                curr++;
            } else {
                curr = curr*10;
                k--;
            }
        }
        return curr;
    }
    int getSteps(int curr, long n) {
        int steps = 0;
        long first = curr, last = curr;
        while(first <= n) {
            steps += min(last, n) - first + 1;
            first = first * 10;
            last = last * 10 + 9;
        }
        return steps;
    }
};