Add solution 1009

leetcode/1009.Complement-of-Base-10-Integer/1009. Complement of Base 10 Integer.go

@@ -0,0 +1,9 @@
+package leetcode
+
+func bitwiseComplement(n int) int {
+	mask := 1
+	for mask < n {
+		mask = (mask << 1) + 1
+	}
+	return mask ^ n
+}

leetcode/1009.Complement-of-Base-10-Integer/1009. Complement of Base 10 Integer_test.go

@@ -0,0 +1,52 @@
+package leetcode
+
+import (
+	"fmt"
+	"testing"
+)
+
+type question1009 struct {
+	para1009
+	ans1009
+}
+
+// para 是参数
+// one 代表第一个参数
+type para1009 struct {
+	n int
+}
+
+// ans 是答案
+// one 代表第一个答案
+type ans1009 struct {
+	one int
+}
+
+func Test_Problem1009(t *testing.T) {
+
+	qs := []question1009{
+
+		{
+			para1009{5},
+			ans1009{2},
+		},
+
+		{
+			para1009{7},
+			ans1009{0},
+		},
+
+		{
+			para1009{10},
+			ans1009{5},
+		},
+	}
+
+	fmt.Printf("------------------------Leetcode Problem 1009------------------------\n")
+
+	for _, q := range qs {
+		_, p := q.ans1009, q.para1009
+		fmt.Printf("【input】:%v       【output】:%v\n", p, bitwiseComplement(p.n))
+	}
+	fmt.Printf("\n\n\n")
+}

leetcode/1009.Complement-of-Base-10-Integer/README.md

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+# [1009. Complement of Base 10 Integer](https://leetcode.com/problems/complement-of-base-10-integer/)
+
+
+## 题目
+
+The **complement** of an integer is the integer you get when you flip all the `0`'s to `1`'s and all the `1`'s to `0`'s in its binary representation.
+
+- For example, The integer `5` is `"101"` in binary and its **complement** is `"010"` which is the integer `2`.
+
+Given an integer `n`, return *its complement*.
+
+**Example 1:**
+
+```
+Input: n = 5
+Output: 2
+Explanation: 5 is "101" in binary, with complement "010" in binary, which is 2 in base-10.
+
+```
+
+**Example 2:**
+
+```
+Input: n = 7
+Output: 0
+Explanation: 7 is "111" in binary, with complement "000" in binary, which is 0 in base-10.
+
+```
+
+**Example 3:**
+
+```
+Input: n = 10
+Output: 5
+Explanation: 10 is "1010" in binary, with complement "0101" in binary, which is 5 in base-10.
+
+```
+
+**Constraints:**
+
+- `0 <= n < 109`
+
+## 题目大意
+
+每个非负整数 N 都有其二进制表示。例如， 5 可以被表示为二进制 "101"，11 可以用二进制 "1011" 表示，依此类推。注意，除 N = 0 外，任何二进制表示中都不含前导零。
+
+二进制的反码表示是将每个 1 改为 0 且每个 0 变为 1。例如，二进制数 "101" 的二进制反码为 "010"。
+
+给你一个十进制数 N，请你返回其二进制表示的反码所对应的十进制整数。
+
+## 解题思路
+
+- 简单题。求一个十进制数的反码，只需要让该数和全 1 的数进行异或计算即可。所以本题重点在如何构造 mask 上。
+
+## 代码
+
+```go
+package leetcode
+
+func bitwiseComplement(n int) int {
+    mask := 1 
+    for mask < n {
+        mask = (mask << 1) + 1
+    }
+    return mask ^ n
+}
+```