[剑指offer]面试题第[44]题[JAVA][数字序列中某一位的数字][找规律]

偏执的太偏执、 2023-03-01 05:36 75阅读 0赞

#### 【问题描述】\[中等\] ####

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#### 【解答思路】 ####

###### 找规律 ######

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**时间复杂度：O(logN) 空间复杂度：O(logN)**

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class Solution { 
        public int findNthDigit(int n) { 
            int digit = 1;
            long start = 1;
            long count = 9;
            while (n > count) {  // 1.
                n -= count;
                digit += 1;
                start *= 10;
                count = digit * start * 9;
            }
            long num = start + (n - 1) / digit; // 2.
            return Long.toString(num).charAt((n - 1) % digit) - '0'; // 3.
        }
    }

#### 【总结】 ####

###### 1. 找规律 画表格 想好再学 ######

###### 2.总结整理归纳 ######

###### 3.注意 越界 注意转换类型 ######

转载链接：https://leetcode-cn.com/problems/shu-zi-xu-lie-zhong-mou-yi-wei-de-shu-zi-lcof/solution/mian-shi-ti-44-shu-zi-xu-lie-zhong-mou-yi-wei-de-6/

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