doocs · yanglbme · Mar 26, 2024 · Mar 26, 2024
diff --git a/solution/0100-0199/0170.Two Sum III - Data structure design/README.md b/solution/0100-0199/0170.Two Sum III - Data structure design/README.md
@@ -68,18 +68,18 @@ twoSum.find(7);  // 没有两个整数加起来等于 7 ，返回 false</pre>
 
 ```python
 class TwoSum:
+
     def __init__(self):
-        self.cnt = Counter()
+        self.cnt = defaultdict(int)
 
     def add(self, number: int) -> None:
         self.cnt[number] += 1
 
     def find(self, value: int) -> bool:
         for x, v in self.cnt.items():
             y = value - x
-            if y in self.cnt:
-                if x != y or v > 1:
-                    return True
+            if y in self.cnt and (x != y or v > 1):
+                return True
         return False
 
 
@@ -104,10 +104,8 @@ class TwoSum {
         for (var e : cnt.entrySet()) {
             int x = e.getKey(), v = e.getValue();
             int y = value - x;
-            if (cnt.containsKey(y)) {
-                if (x != y || v > 1) {
-                    return true;
-                }
+            if (cnt.containsKey(y) && (x != y || v > 1)) {
+                return true;
             }
         }
         return false;
@@ -135,10 +133,8 @@ public:
     bool find(int value) {
         for (auto& [x, v] : cnt) {
             long y = (long) value - x;
-            if (cnt.count(y)) {
-                if (x != y || v > 1) {
-                    return true;
-                }
+            if (cnt.contains(y) && (x != y || v > 1)) {
+                return true;
             }
         }
         return false;
@@ -166,7 +162,7 @@ func Constructor() TwoSum {
 }
 
 func (this *TwoSum) Add(number int) {
-	this.cnt[number]++
+	this.cnt[number] += 1
 }
 
 func (this *TwoSum) Find(value int) bool {
@@ -187,6 +183,34 @@ func (this *TwoSum) Find(value int) bool {
  */
 ```
 
+```ts
+class TwoSum {
+    private cnt: Map<number, number> = new Map();
+    constructor() {}
+
+    add(number: number): void {
+        this.cnt.set(number, (this.cnt.get(number) || 0) + 1);
+    }
+
+    find(value: number): boolean {
+        for (const [x, v] of this.cnt) {
+            const y = value - x;
+            if (this.cnt.has(y) && (x !== y || v > 1)) {
+                return true;
+            }
+        }
+        return false;
+    }
+}
+
+/**
+ * Your TwoSum object will be instantiated and called as such:
+ * var obj = new TwoSum()
+ * obj.add(number)
+ * var param_2 = obj.find(value)
+ */
+```
+
 <!-- tabs:end -->
 
 <!-- end -->
diff --git a/solution/0100-0199/0170.Two Sum III - Data structure design/README_EN.md b/solution/0100-0199/0170.Two Sum III - Data structure design/README_EN.md
@@ -46,24 +46,37 @@ twoSum.find(7);  // No two integers sum up to 7, return false
 
 ## Solutions
 
-### Solution 1
+### Solution 1: Hash Table
+
+We use a hash table `cnt` to store the count of each number.
+
+When the `add` method is called, we increment the count of the number `number`.
+
+When the `find` method is called, we iterate over the hash table `cnt`. For each key `x`, we check if `value - x` is also a key in the hash table `cnt`. If it is, we check if `x` is equal to `value - x`. If they are not equal, it means we have found a pair of numbers whose sum is `value`, and we return `true`. If they are equal, we check if the count of `x` is greater than `1`. If it is, it means we have found a pair of numbers whose sum is `value`, and we return `true`. If it is less than or equal to `1`, it means we have not found a pair of numbers whose sum is `value`, and we continue to iterate over the hash table `cnt`. If we have not found a pair after the iteration, we return `false`.
+
+Time complexity:
+
+-   The time complexity of the `add` method is $O(1)$.
+-   The time complexity of the `find` method is $O(n)$.
+
+Space complexity is $O(n)$, where $n$ is the size of the hash table `cnt`.
 
 <!-- tabs:start -->
 
 ```python
 class TwoSum:
+
     def __init__(self):
-        self.cnt = Counter()
+        self.cnt = defaultdict(int)
 
     def add(self, number: int) -> None:
         self.cnt[number] += 1
 
     def find(self, value: int) -> bool:
         for x, v in self.cnt.items():
             y = value - x
-            if y in self.cnt:
-                if x != y or v > 1:
-                    return True
+            if y in self.cnt and (x != y or v > 1):
+                return True
         return False
 
 
@@ -88,10 +101,8 @@ class TwoSum {
         for (var e : cnt.entrySet()) {
             int x = e.getKey(), v = e.getValue();
             int y = value - x;
-            if (cnt.containsKey(y)) {
-                if (x != y || v > 1) {
-                    return true;
-                }
+            if (cnt.containsKey(y) && (x != y || v > 1)) {
+                return true;
             }
         }
         return false;
@@ -119,10 +130,8 @@ public:
     bool find(int value) {
         for (auto& [x, v] : cnt) {
             long y = (long) value - x;
-            if (cnt.count(y)) {
-                if (x != y || v > 1) {
-                    return true;
-                }
+            if (cnt.contains(y) && (x != y || v > 1)) {
+                return true;
             }
         }
         return false;
@@ -150,7 +159,7 @@ func Constructor() TwoSum {
 }
 
 func (this *TwoSum) Add(number int) {
-	this.cnt[number]++
+	this.cnt[number] += 1
 }
 
 func (this *TwoSum) Find(value int) bool {
@@ -171,6 +180,34 @@ func (this *TwoSum) Find(value int) bool {
  */
 ```
 
+```ts
+class TwoSum {
+    private cnt: Map<number, number> = new Map();
+    constructor() {}
+
+    add(number: number): void {
+        this.cnt.set(number, (this.cnt.get(number) || 0) + 1);
+    }
+
+    find(value: number): boolean {
+        for (const [x, v] of this.cnt) {
+            const y = value - x;
+            if (this.cnt.has(y) && (x !== y || v > 1)) {
+                return true;
+            }
+        }
+        return false;
+    }
+}
+
+/**
+ * Your TwoSum object will be instantiated and called as such:
+ * var obj = new TwoSum()
+ * obj.add(number)
+ * var param_2 = obj.find(value)
+ */
+```
+
 <!-- tabs:end -->
 
 <!-- end -->
diff --git a/solution/0100-0199/0170.Two Sum III - Data structure design/Solution.cpp b/solution/0100-0199/0170.Two Sum III - Data structure design/Solution.cpp
@@ -10,10 +10,8 @@ class TwoSum {
     bool find(int value) {
         for (auto& [x, v] : cnt) {
             long y = (long) value - x;
-            if (cnt.count(y)) {
-                if (x != y || v > 1) {
-                    return true;
-                }
+            if (cnt.contains(y) && (x != y || v > 1)) {
+                return true;
             }
         }
         return false;

diff --git a/solution/0100-0199/0170.Two Sum III - Data structure design/Solution.go b/solution/0100-0199/0170.Two Sum III - Data structure design/Solution.go
@@ -7,7 +7,7 @@ func Constructor() TwoSum {
 }
 
 func (this *TwoSum) Add(number int) {
-	this.cnt[number]++
+	this.cnt[number] += 1
 }
 
 func (this *TwoSum) Find(value int) bool {

diff --git a/solution/0100-0199/0170.Two Sum III - Data structure design/Solution.java b/solution/0100-0199/0170.Two Sum III - Data structure design/Solution.java
@@ -12,10 +12,8 @@ public boolean find(int value) {
         for (var e : cnt.entrySet()) {
             int x = e.getKey(), v = e.getValue();
             int y = value - x;
-            if (cnt.containsKey(y)) {
-                if (x != y || v > 1) {
-                    return true;
-                }
+            if (cnt.containsKey(y) && (x != y || v > 1)) {
+                return true;
             }
         }
         return false;

diff --git a/solution/0100-0199/0170.Two Sum III - Data structure design/Solution.py b/solution/0100-0199/0170.Two Sum III - Data structure design/Solution.py
@@ -1,16 +1,16 @@
 class TwoSum:
+
     def __init__(self):
-        self.cnt = Counter()
+        self.cnt = defaultdict(int)
 
     def add(self, number: int) -> None:
         self.cnt[number] += 1
 
     def find(self, value: int) -> bool:
         for x, v in self.cnt.items():
             y = value - x
-            if y in self.cnt:
-                if x != y or v > 1:
-                    return True
+            if y in self.cnt and (x != y or v > 1):
+                return True
         return False
 
 

diff --git a/solution/0100-0199/0170.Two Sum III - Data structure design/Solution.ts b/solution/0100-0199/0170.Two Sum III - Data structure design/Solution.ts
@@ -0,0 +1,25 @@
+class TwoSum {
+    private cnt: Map<number, number> = new Map();
+    constructor() {}
+
+    add(number: number): void {
+        this.cnt.set(number, (this.cnt.get(number) || 0) + 1);
+    }
+
+    find(value: number): boolean {
+        for (const [x, v] of this.cnt) {
+            const y = value - x;
+            if (this.cnt.has(y) && (x !== y || v > 1)) {
+                return true;
+            }
+        }
+        return false;
+    }
+}
+
+/**
+ * Your TwoSum object will be instantiated and called as such:
+ * var obj = new TwoSum()
+ * obj.add(number)
+ * var param_2 = obj.find(value)
+ */
diff --git a/solution/0100-0199/0171.Excel Sheet Column Number/README.md b/solution/0100-0199/0171.Excel Sheet Column Number/README.md
@@ -56,27 +56,33 @@ AB -&gt; 28
 
 ## 解法
 
-### 方法一
+### 方法一：进制转换
+
+Excel 表格中的列名称是一种 26 进制的表示方法。例如，"AB" 表示的列序号是 $1 \times 26 + 2 = 28$。
+
+因此，我们可以遍历字符串 `columnTitle`，将每个字符转换为对应的数值，然后计算结果即可。
+
+时间复杂度 $O(n)$，其中 $n$ 是字符串 `columnTitle` 的长度。空间复杂度 $O(1)$。
 
 <!-- tabs:start -->
 
 ```python
 class Solution:
     def titleToNumber(self, columnTitle: str) -> int:
-        res = 0
-        for c in columnTitle:
-            res = res * 26 + (ord(c) - ord('A') + 1)
-        return res
+        ans = 0
+        for c in map(ord, columnTitle):
+            ans = ans * 26 + c - ord("A") + 1
+        return ans
 ```
 
 ```java
 class Solution {
     public int titleToNumber(String columnTitle) {
-        int res = 0;
-        for (char c : columnTitle.toCharArray()) {
-            res = res * 26 + (c - 'A' + 1);
+        int ans = 0;
+        for (int i = 0; i < columnTitle.length(); ++i) {
+            ans = ans * 26 + (columnTitle.charAt(i) - 'A' + 1);
         }
-        return res;
+        return ans;
     }
 }
 ```
@@ -85,32 +91,43 @@ class Solution {
 class Solution {
 public:
     int titleToNumber(string columnTitle) {
-        int res = 0;
-        for (char c : columnTitle) {
-            res = res * 26 + (c - 'A' + 1);
+        int ans = 0;
+        for (char& c : columnTitle) {
+            ans = ans * 26 + (c - 'A' + 1);
         }
-        return res;
+        return ans;
     }
 };
 ```
 
 ```go
-func titleToNumber(columnTitle string) int {
-	res := 0
+func titleToNumber(columnTitle string) (ans int) {
 	for _, c := range columnTitle {
-		res = res*26 + int(c-'A'+1)
+		ans = ans*26 + int(c-'A'+1)
 	}
-	return res
+	return
 }
 ```
 
 ```ts
 function titleToNumber(columnTitle: string): number {
-    let res: number = 0;
-    for (let char of columnTitle) {
-        res = res * 26 + char.charCodeAt(0) - 64;
+    let ans: number = 0;
+    for (const c of columnTitle) {
+        ans = ans * 26 + (c.charCodeAt(0) - 'A'.charCodeAt(0) + 1);
+    }
+    return ans;
+}
+```
+
+```cs
+public class Solution {
+    public int TitleToNumber(string columnTitle) {
+        int ans = 0;
+        foreach (char c in columnTitle) {
+            ans = ans * 26 + c - 'A' + 1;
+        }
+        return ans;
     }
-    return res;
 }
 ```