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69 lines
1.4 KiB
Markdown
69 lines
1.4 KiB
Markdown
# [2180. Count Integers With Even Digit Sum](https://leetcode.com/problems/count-integers-with-even-digit-sum/)
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## 题目
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Given a positive integer `num`, return *the number of positive integers **less than or equal to*** `num` *whose digit sums are **even***.
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The **digit sum** of a positive integer is the sum of all its digits.
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**Example 1:**
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```
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Input: num = 4
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Output: 2
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Explanation:
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The only integers less than or equal to 4 whose digit sums are even are 2 and 4.
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```
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**Example 2:**
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```
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Input: num = 30
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Output: 14
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Explanation:
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The 14 integers less than or equal to 30 whose digit sums are even are
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2, 4, 6, 8, 11, 13, 15, 17, 19, 20, 22, 24, 26, and 28.
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```
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**Constraints:**
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- `1 <= num <= 1000`
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## 题目大意
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给你一个正整数 num ，请你统计并返回 小于或等于 num 且各位数字之和为 偶数 的正整数的数目。
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正整数的 各位数字之和 是其所有位上的对应数字相加的结果。
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## 解题思路
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- 简单题。依照题意，计算每个数的各位数字之和，如何和为偶数，则统计结果加一。最后输出统计结果即可。
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## 代码
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```go
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package leetcode
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func countEven(num int) int {
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count := 0
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for i := 1; i <= num; i++ {
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if addSum(i)%2 == 0 {
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count++
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}
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}
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return count
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}
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func addSum(num int) int {
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sum := 0
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tmp := num
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for tmp != 0 {
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sum += tmp % 10
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tmp = tmp / 10
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}
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return sum
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}
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``` |