Add solution and test-cases for problem 1432

Author: 0xff-dev

leetcode/1401-1500/1432.Max-Difference-You-Can-Get-From-Changing-an-Integer/README.md

@@ -0,0 +1,42 @@
+# [1432.Max Difference You Can Get From Changing an Integer][title]
+
+## Description
+
+You are given an integer `num`. You will apply the following steps to num **two** separate times:
+
+- Pick a digit `x` `(0 <= x <= 9)`.
+- Pick another digit `y` `(0 <= y <= 9)`. Note `y` can be equal to `x`.
+- Replace all the occurrences of `x` in the decimal representation of `num` by `y`.
+
+Let `a` and `b` be the two results from applying the operation to `num` independently.
+
+Return the max difference between `a` and `b`.
+
+Note that neither `a` nor `b` may have any leading zeros, and **must not** be 0.
+
+**Example 1:**
+
+```
+Input: num = 555
+Output: 888
+Explanation: The first time pick x = 5 and y = 9 and store the new integer in a.
+The second time pick x = 5 and y = 1 and store the new integer in b.
+We have now a = 999 and b = 111 and max difference = 888
+```
+
+**Example 2:**
+
+```
+Input: num = 9
+Output: 8
+Explanation: The first time pick x = 9 and y = 9 and store the new integer in a.
+The second time pick x = 9 and y = 1 and store the new integer in b.
+We have now a = 9 and b = 1 and max difference = 8
+```
+
+## 结语
+
+如果你同我一样热爱数据结构、算法、LeetCode，可以关注我 GitHub 上的 LeetCode 题解：[awesome-golang-algorithm][me]
+
+[title]: https://leetcode.com/problems/max-difference-you-can-get-from-changing-an-integer/
+[me]: https://github.com/kylesliu/awesome-golang-algorithm

leetcode/1401-1500/1432.Max-Difference-You-Can-Get-From-Changing-an-Integer/Solution.go

@@ -1,5 +1,53 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+func Solution(num int) int {
+	digits := make([]int, 0)
+	for num > 0 {
+		digits = append(digits, num%10)
+		num /= 10
+	}
+	cp := make([]int, len(digits))
+	copy(cp, digits)
+
+	i := len(digits) - 1
+	remap := -1
+	for ; i >= 0; i-- {
+		if cp[i] != 9 {
+			remap = cp[i]
+			break
+		}
+	}
+	for ; i >= 0; i-- {
+		if cp[i] == remap {
+			cp[i] = 9
+		}
+	}
+
+	i = len(digits) - 1
+	target := 1
+	if digits[i] == 1 {
+		target = 0
+	}
+
+	remap = -1
+	for ; i >= 0; i-- {
+		if digits[i] == 0 {
+			continue
+		}
+		if digits[i] != 1 {
+			remap = digits[i]
+			break
+		}
+	}
+	for ; i >= 0; i-- {
+		if digits[i] == remap {
+			digits[i] = target
+		}
+	}
+	a, b := 0, 0
+	for i := len(digits) - 1; i >= 0; i-- {
+		a = a*10 + cp[i]
+		b = b*10 + digits[i]
+	}
+	return a - b
 }

leetcode/1401-1500/1432.Max-Difference-You-Can-Get-From-Changing-an-Integer/Solution_test.go

@@ -10,12 +10,11 @@ func TestSolution(t *testing.T) {
 	//	测试用例
 	cases := []struct {
 		name   string
-		inputs bool
-		expect bool
+		inputs int
+		expect int
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", 555, 888},
+		{"TestCase2", 9, 8},
 	}
 
 	//	开始测试
@@ -30,10 +29,10 @@ func TestSolution(t *testing.T) {
 	}
 }
 
-//	压力测试
+// 压力测试
 func BenchmarkSolution(b *testing.B) {
 }
 
-//	使用案列
+// 使用案列
 func ExampleSolution() {
 }