标签：rip code input man pre note sequence 题目 return
Find the nth digit of the infinite integer sequence 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, ...
Note:
n is positive and will fit within the range of a 32-bit signed integer (n < 231).
Example 1:
Input: 3 Output: 3
Example 2:
Input: 11 Output: 0 Explanation: The 11th digit of the sequence 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, ... is a 0, which is part of the number 10.
class Solution { public: int findNthDigit(int n) { // 1. calc how many digits the number has. long base = 9, digits = 1; while (n - base * digits > 0) { n -= base * digits; base *= 10; digits++; } // 2. calc what the number is. int index = n % digits; if (index == 0) index = digits; long num = 1; for (int i = 1; i < digits; i++) num *= 10; num += (index == digits) ? n / digits - 1 : n / digits; // 3. find out which digit in the number. for (int i = index; i < digits; i++) num /= 10; return num % 10; } }; // 3 ms
标签：rip code input man pre note sequence 题目 return
原文地址：http://www.cnblogs.com/immjc/p/7994218.html
