第一周作业

Author: 尹若朋

Week_01/id_7/LeetCode_189_7.cs

@@ -0,0 +1,22 @@
+/*
+ * @lc app=leetcode.cn id=189 lang=csharp
+ *
+ * [189] 旋转数组
+ */
+public class Solution {
+    public void Rotate (int[] nums, int k) {
+        k %= nums.Length;
+        Reverse (nums, 0, nums.Length - 1);
+        Reverse (nums, 0, k - 1);
+        Reverse (nums, k, nums.Length - 1);
+    }
+    public void Reverse (int[] nums, int start, int end) {
+        while (start < end) {
+            int temp = nums[start];
+            nums[start] = nums[end];
+            nums[end] = temp;
+            start++;
+            end--;
+        }
+    }
+}

Week_01/id_7/LeetCode_21_7.cs

@@ -0,0 +1,20 @@
+/*
+ * @lc app=leetcode.cn id=21 lang=csharp
+ *
+ * [21] 合并两个有序链表
+ */
+public class Solution {
+    public ListNode MergeTwoLists (ListNode l1, ListNode l2) {
+        if (l1 == null) {
+            return l2;
+        } else if (l2 == null) {
+            return l1;
+        } else if (l1.val < l2.val) {
+            l1.next = MergeTwoLists (l1.next, l2);
+            return l1;
+        } else {
+            l2.next = MergeTwoLists (l1, l2.next);
+            return l2;
+        }
+    }
+}

Week_01/id_7/LeetCode_26_7.cs

@@ -0,0 +1,15 @@
+public class Solution {
+    public int RemoveDuplicates (int[] nums) {
+        if (nums.Length == 0) return 0;
+        if (nums.Length == 1) return 1;
+
+        int count = 0;
+        for (int i = 1; i < nums.Length; i++) {
+            if (nums[count] != nums[i]) {
+                nums[++count] = nums[i];
+            }
+        }
+
+        return count + 1;
+    }
+}

Week_01/id_7/LeetCode_283_7.cs

@@ -0,0 +1,15 @@
+public class Solution {
+    public void MoveZeroes (int[] nums) {
+        if (nums == null || nums.Length == 0 || nums.Length == 1) return;
+
+        int count = 0;
+        for (int i = 0; i < nums.Length; i++) {
+            if (nums[i] != 0) {
+                int temp = nums[count];
+                nums[count] = nums[i];
+                nums[i] = temp;
+                count++;
+            }
+        }
+    }
+}

Week_01/id_7/LeetCode_66_7.cs

@@ -0,0 +1,24 @@
+/*
+ * @lc app=leetcode.cn id=66 lang=csharp
+ *
+ * [66] 加一
+ *
+ */
+using System;
+
+public class Solution {
+    public int[] PlusOne (int[] digits) {
+        for (int i = digits.Length - 1; i >= 0; i--) {
+            if ((digits[i] + 1) % 10 != 0) {
+                digits[i] += 1;
+                return digits;
+            } else {
+                digits[i] = 0;
+            }
+        }
+
+        digits = new int[digits.Length + 1];
+        digits[0] = 1;
+        return digits;
+    }
+}

Week_01/id_7/LeetCode_70_7.cs

@@ -0,0 +1,22 @@
+public class Solution {
+    Dictionary<int, int> dic = new Dictionary<int, int> ();
+    public int ClimbStairs (int n) {
+        if (n == 1) return 1;
+        if (n == 2) return 2;
+        int A;
+        if (dic.ContainsKey (n - 1)) {
+            A = dic[n - 1];
+        } else {
+            A = ClimbStairs (n - 1);
+            dic.Add (n - 1, A);
+        }
+        int B;
+        if (dic.ContainsKey (n - 2)) {
+            B = dic[n - 2];
+        } else {
+            B = ClimbStairs (n - 2);
+            dic.Add (n - 2, B);
+        }
+        return A + B;
+    }
+}

Week_01/id_7/LeetCode_88_7.cs

@@ -0,0 +1,19 @@
+/*
+ * @lc app=leetcode.cn id=88 lang=csharp
+ *
+ * [88] 合并两个有序数组
+ */
+using System;
+
+public class Solution {
+    public void Merge (int[] nums1, int m, int[] nums2, int n) {
+        int p = m + n - 1, p1 = m - 1, p2 = n - 1;
+        while (p1 >= 0 && p2 >= 0) {
+            nums1[p--] = nums1[p1] > nums2[p2] ? nums1[p1--] : nums2[p2--];
+        }
+
+        if (p2 >= 0) {
+            Array.Copy (nums2, 0, nums1, 0, p2 + 1);
+        }
+    }
+}