feat: add csharp solution to lc problem: No.0264. Ugly Number II

Author: yanglbme

README.md

@@ -182,6 +182,7 @@
 - [等差数列划分](./solution/0400-0499/0413.Arithmetic%20Slices/README.md)
 - [解码方法](./solution/0000-0099/0091.Decode%20Ways/README.md)
 - [不同的二叉搜索树](./solution/0000-0099/0096.Unique%20Binary%20Search%20Trees/README.md)
+- [丑数 II](./solution/0200-0299/0264.Ugly%20Number%20II/README.md)
 - [礼物的最大价值](./lcof/面试题47.%20礼物的最大价值/README.md)
 - [最小路径和](./solution/0000-0099/0064.Minimum%20Path%20Sum/README.md)
 - [最长上升子序列](./solution/0300-0399/0300.Longest%20Increasing%20Subsequence/README.md)

README_EN.md

@@ -176,6 +176,7 @@ Complete solutions to [LeetCode](https://leetcode.com/problemset/all/), [LCOF](h
 - [Arithmetic Slices](./solution/0400-0499/0413.Arithmetic%20Slices/README_EN.md)
 - [Decode Ways](./solution/0000-0099/0091.Decode%20Ways/README_EN.md)
 - [Unique Binary Search Trees](./solution/0000-0099/0096.Unique%20Binary%20Search%20Trees/README_EN.md)
+- [Ugly Number II](./solution/0200-0299/0264.Ugly%20Number%20II/README_EN.md)
 - [Minimum Path Sum](./solution/0000-0099/0064.Minimum%20Path%20Sum/README_EN.md)
 - [Longest Increasing Subsequence](./solution/0300-0399/0300.Longest%20Increasing%20Subsequence/README_EN.md)
 - [Russian Doll Envelopes](./solution/0300-0399/0354.Russian%20Doll%20Envelopes/README_EN.md)

solution/0200-0299/0264.Ugly Number II/README.md

@@ -71,7 +71,7 @@ class Solution:
                 p3 += 1
             if dp[i] == next5:
                 p5 += 1
-        return dp[n - 1]
+        return dp[-1]
 ```
 
 ### **Java**
@@ -174,6 +174,36 @@ func min(a, b int) int {
 }
 ```
 
+### **C#**
+
+```cs
+public class Solution {
+    public int NthUglyNumber(int n) {
+        int[] dp = new int[n];
+        dp[0] = 1;
+        int p2 = 0, p3 = 0, p5 = 0;
+        for (int i = 1; i < n; ++i)
+        {
+            int next2 = dp[p2] * 2, next3 = dp[p3] * 3, next5 = dp[p5] * 5;
+            dp[i] = Math.Min(next2, Math.Min(next3, next5));
+            if (dp[i] == next2)
+            {
+                ++p2;
+            }
+            if (dp[i] == next3)
+            {
+                ++p3;
+            }
+            if (dp[i] == next5)
+            {
+                ++p5;
+            }
+        }
+        return dp[n - 1];
+    }
+}
+```
+
 ### **...**
 
 ```

solution/0200-0299/0264.Ugly Number II/README_EN.md

@@ -53,7 +53,7 @@ class Solution:
                 p3 += 1
             if dp[i] == next5:
                 p5 += 1
-        return dp[n - 1]
+        return dp[-1]
 ```
 
 ### **Java**
@@ -154,6 +154,36 @@ func min(a, b int) int {
 }
 ```
 
+### **C#**
+
+```cs
+public class Solution {
+    public int NthUglyNumber(int n) {
+        int[] dp = new int[n];
+        dp[0] = 1;
+        int p2 = 0, p3 = 0, p5 = 0;
+        for (int i = 1; i < n; ++i)
+        {
+            int next2 = dp[p2] * 2, next3 = dp[p3] * 3, next5 = dp[p5] * 5;
+            dp[i] = Math.Min(next2, Math.Min(next3, next5));
+            if (dp[i] == next2)
+            {
+                ++p2;
+            }
+            if (dp[i] == next3)
+            {
+                ++p3;
+            }
+            if (dp[i] == next5)
+            {
+                ++p5;
+            }
+        }
+        return dp[n - 1];
+    }
+}
+```
+
 ### **...**
 
 ```

solution/0200-0299/0264.Ugly Number II/Solution.cs

@@ -0,0 +1,25 @@
+public class Solution {
+    public int NthUglyNumber(int n) {
+        int[] dp = new int[n];
+        dp[0] = 1;
+        int p2 = 0, p3 = 0, p5 = 0;
+        for (int i = 1; i < n; ++i)
+        {
+            int next2 = dp[p2] * 2, next3 = dp[p3] * 3, next5 = dp[p5] * 5;
+            dp[i] = Math.Min(next2, Math.Min(next3, next5));
+            if (dp[i] == next2)
+            {
+                ++p2;
+            }
+            if (dp[i] == next3)
+            {
+                ++p3;
+            }
+            if (dp[i] == next5)
+            {
+                ++p5;
+            }
+        }
+        return dp[n - 1];
+    }
+}