Merge pull request #933 from 0xff-dev/726

Add solution and test-cases for problem 726

Author: 6boris

leetcode/701-800/0726.Number-of-Atoms/README.md

@@ -1,28 +1,49 @@
 # [726.Number of Atoms][title]
 
-> [!WARNING|style:flat]
-> This question is temporarily unanswered if you have good ideas. Welcome to [Create Pull Request PR](https://github.com/kylesliu/awesome-golang-algorithm)
-
 ## Description
+Given a string `formula` representing a chemical formula, return the count of each atom.
+
+The atomic element always starts with an uppercase character, then zero or more lowercase letters, representing the name.
+
+One or more digits representing that element's count may follow if the count is greater than `1`. If the count is `1`, no digits will follow.
+
+- For example, `"H2O"` and `"H2O2"` are possible, but `"H1O2"` is impossible.
+
+Two formulas are concatenated together to produce another formula.
+
+- For example, `"H2O2He3Mg4"` is also a formula.
+
+A formula placed in parentheses, and a count (optionally added) is also a formula.
+
+- For example, `"(H2O2)"` and `"(H2O2)3"` are formulas.
+
+Return the count of all elements as a string in the following form: the first name (in sorted order), followed by its count (if that count is more than `1`), followed by the second name (in sorted order), followed by its count (if that count is more than `1`), and so on.
+
+The test cases are generated so that all the values in the output fit in a **32-bit** integer.
 
 **Example 1:**
 
 ```
-Input: a = "11", b = "1"
-Output: "100"
+Input: formula = "H2O"
+Output: "H2O"
+Explanation: The count of elements are {'H': 2, 'O': 1}.
 ```
 
-## 题意
-> ...
+**Example 2:**
 
-## 题解
-
-### 思路1
-> ...
-Number of Atoms
-```go
+```
+Input: formula = "Mg(OH)2"
+Output: "H2MgO2"
+Explanation: The count of elements are {'H': 2, 'Mg': 1, 'O': 2}.
 ```
 
+**Example 3:**
+
+```
+Input: formula = "K4(ON(SO3)2)2"
+Output: "K4N2O14S4"
+Explanation: The count of elements are {'K': 4, 'N': 2, 'O': 14, 'S': 4}.
+```
 
 ## 结语
 

leetcode/701-800/0726.Number-of-Atoms/Solution.go

@@ -1,5 +1,83 @@
 package Solution
 
-func Solution(x bool) bool {
-	return x
+import (
+	"fmt"
+	"sort"
+	"strings"
+)
+
+type tmp726 struct {
+	k string
+	c int
+}
+
+func Solution(formula string) string {
+	stack := make([]map[string]int, 0)
+	count := make(map[string]int)
+	i, l := 0, len(formula)
+	for i < l {
+		cur := formula[i]
+		if cur >= 'A' && cur <= 'Z' {
+			start := i
+			i++
+			// 判断后面是否还跟着小写字母
+			for ; i < l && formula[i] >= 'a' && formula[i] <= 'z'; i++ {
+			}
+			// 一个元素
+			key := formula[start:i]
+			// 判断数字
+			c := 0
+			for ; i < l && formula[i] >= '0' && formula[i] <= '9'; i++ {
+				c = c*10 + int(formula[i]-'0')
+			}
+
+			if c == 0 {
+				c = 1
+			}
+			count[key] += c
+			continue
+		}
+		if cur == '(' {
+			stack = append(stack, count)
+			count = map[string]int{}
+			i++
+			continue
+		}
+		pc := 0
+		i++
+		for ; i < l && formula[i] >= '0' && formula[i] <= '9'; i++ {
+			pc = pc*10 + int(formula[i]-'0')
+		}
+		if pc == 0 {
+			pc = 1
+		}
+		for k := range count {
+			count[k] *= pc
+		}
+		if tl := len(stack); tl > 0 {
+			top := stack[tl-1]
+			stack = stack[:tl-1]
+			for k, c := range top {
+				count[k] += c
+			}
+		}
+
+	}
+
+	list := make([]tmp726, 0)
+	for k, v := range count {
+		list = append(list, tmp726{k, v})
+	}
+	sort.Slice(list, func(i, j int) bool {
+		return list[i].k < list[j].k
+	})
+	buf := strings.Builder{}
+	for _, i := range list {
+		w := i.k
+		if i.c != 1 {
+			w += fmt.Sprintf("%d", i.c)
+		}
+		buf.WriteString(w)
+	}
+	return buf.String()
 }

leetcode/701-800/0726.Number-of-Atoms/Solution_test.go

@@ -10,12 +10,14 @@ func TestSolution(t *testing.T) {
 	//	测试用例
 	cases := []struct {
 		name   string
-		inputs bool
-		expect bool
+		inputs string
+		expect string
 	}{
-		{"TestCase", true, true},
-		{"TestCase", true, true},
-		{"TestCase", false, false},
+		{"TestCase1", "H2O", "H2O"},
+		{"TestCase2", "Mg(OH)2", "H2MgO2"},
+		{"TestCase3", "K4(ON(SO3)2)2", "K4N2O14S4"},
+		{"TestCase4", "H2(H3)2", "H8"},
+		{"TestCase5", "H11He49NO35B7N46Li20", "B7H11He49Li20N47O35"},
 	}
 
 	//	开始测试
@@ -30,10 +32,10 @@ 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() {
 }