day31

1.剑指 Offer 14- II. 剪绳子 II

 1 class Solution {
 2 public:
 3     int cuttingRope(int n) {
 4        if(n <= 3)  return n - 1;
 5        long res = 1;
 6        while(n > 4){
 7            n -= 3;
 8            res = (res * 3) % 1000000007;
 9        }
10        res = (res * n) % 1000000007;
11        return (int)res;
12     }
13 };

2.剑指 Offer 43. 1～n 整数中 1 出现的次数

  https://leetcode.cn/leetbook/read/illustration-of-algorithm/57nyhd/

 1 class Solution {
 2 public:
 3     int countDigitOne(int n) {
 4        long digit = 1;
 5        int high = n / 10,cur = n % 10,low = 0,res = 0;
 6        while(high != 0 || cur != 0){
 7            if(cur == 0)  res += high * digit;
 8            else if(cur == 1)  res += (high * digit) + low + 1;
 9            else  res += (high + 1) * digit;
10            low += cur * digit;
11            cur = high % 10;
12            high /= 10;
13            digit *= 10;
14        }
15        return res;
16     }
17 };

3.剑指 Offer 44. 数字序列中某一位的数字

 https://leetcode.cn/leetbook/read/illustration-of-algorithm/57w6b3/

 1 class Solution {
 2 public:
 3     int findNthDigit(int n) {
 4       int digit = 1;
 5       long start = 1;
 6       long count = 9;
 7       while(n > count){
 8          n -= count;
 9          digit += 1;
10          start *= 10;
11          count = start * 9 * digit;
12       }
13       int num = start + (n - 1) / digit;
14       return to_string(num)[(n - 1) % digit] - '0';
15     }
16 };

 

posted @ 2022-07-28 17:52  balabalahhh  阅读(27)  评论(0)    收藏  举报