LeetCode（剑指 Offer）- 43. 1～n 整数中 1 出现的次数

Posted 2022-12-09 放羊的牧码

题目链接：点击打开链接

题目大意：略

解题思路

相关企业

• 亚马逊
• 微软（Microsoft）
• 苹果（Apple）

AC 代码

• Java

class Solution 
    public int countDigitOne(int n) 
        int digit = 1, res = 0;
        int high = n / 10, cur = n % 10, low = 0;
        while(high != 0 || cur != 0) 
            if(cur == 0) res += high * digit;
            else if(cur == 1) res += high * digit + low + 1;
            else res += (high + 1) * digit;
            low += cur * digit;
            cur = high % 10;
            high /= 10;
            digit *= 10;
        
        return res;
    

• C++

class Solution 
public:
    int countDigitOne(int n) 
        long digit = 1;
        int high = n / 10, cur = n % 10, low = 0, res = 0;
        while(high != 0 || cur != 0) 
            if(cur == 0) res += high * digit;
            else if(cur == 1) res += high * digit + low + 1;
            else res += (high + 1) * digit;
            low += cur * digit;
            cur = high % 10;
            high /= 10;
            digit *= 10;
        
        return res;
    
;