2024-1月 13 14日复刷

src/main/java/cn/whaifree/redo/redo24_1_7/LeetCode15.java

@@ -1,4 +1,4 @@
-package cn.whaifree.redo;
+package cn.whaifree.redo.redo24_1_7;
 
 
 import org.junit.Test;

src/main/java/cn/whaifree/redo/redo24_1_7/LeetCode151.java

@@ -1,4 +1,4 @@
-package cn.whaifree.redo;
+package cn.whaifree.redo.redo24_1_7;
 
 import org.junit.Test;
 

src/main/java/cn/whaifree/redo/redo24_1_7/LeetCode18.java

@@ -1,4 +1,4 @@
-package cn.whaifree.redo;
+package cn.whaifree.redo.redo24_1_7;
 
 import org.junit.Test;
 

src/main/java/cn/whaifree/redo/redo24_1_7/LeetCode202.java

@@ -1,4 +1,4 @@
-package cn.whaifree.redo;
+package cn.whaifree.redo.redo24_1_7;
 
 import org.junit.Test;
 

src/main/java/cn/whaifree/redo/redo24_1_7/LeetCode203_false.java

@@ -1,10 +1,10 @@
-package cn.whaifree.redo;
+package cn.whaifree.redo.redo24_1_7;
 
 
 import cn.whaifree.leetCode.model.ListNode;
 import org.junit.Test;
 
-public class LeetCode203 {
+public class LeetCode203_false {
 
     @Test
     public void test(){

src/main/java/cn/whaifree/redo/redo24_1_7/LeetCode206_false.java

@@ -1,10 +1,10 @@
-package cn.whaifree.redo;
+package cn.whaifree.redo.redo24_1_7;
 
 import cn.whaifree.leetCode.model.ListNode;
 import org.junit.Test;
 
 // 递归逆转链表
-public class LeetCode206 {
+public class LeetCode206_false {
 
     @Test
     public void test() {

src/main/java/cn/whaifree/redo/redo24_1_7/LeetCode209_false.java

@@ -1,8 +1,8 @@
-package cn.whaifree.redo;
+package cn.whaifree.redo.redo24_1_7;
 
 import org.junit.Test;
 
-public class LeetCode209 {
+public class LeetCode209_false {
 
     @Test
     public void test() {

src/main/java/cn/whaifree/redo/redo24_1_7/LeetCode2487_false.java

@@ -1,9 +1,9 @@
-package cn.whaifree.redo;
+package cn.whaifree.redo.redo24_1_7;
 
 import cn.whaifree.leetCode.model.ListNode;
 import org.junit.Test;
 
-public class LeetCode2487 {
+public class LeetCode2487_false {
 
     @Test
     public void test() {

src/main/java/cn/whaifree/redo/redo24_1_7/LeetCode287_false.java

@@ -1,4 +1,4 @@
-package cn.whaifree.redo;
+package cn.whaifree.redo.redo24_1_7;
 
 import cn.hutool.core.lang.hash.Hash;
 import org.junit.Test;
@@ -6,7 +6,7 @@ import org.junit.Test;
 import java.util.HashSet;
 import java.util.Set;
 
-public class LeetCode287 {
+public class LeetCode287_false {
 
     @Test
     public void test() {

src/main/java/cn/whaifree/redo/redo24_1_7/LeetCode28_false.java

@@ -1,8 +1,8 @@
-package cn.whaifree.redo;
+package cn.whaifree.redo.redo24_1_7;
 
 import org.junit.Test;
 
-public class LeetCode28 {
+public class LeetCode28_false {
 
     @Test
     public void test() {

src/main/java/cn/whaifree/redo/redo_24_1_13/LeetCode203.java

@@ -0,0 +1,10 @@
+package cn.whaifree.redo.redo_24_1_13;
+
+/**
+ * @version 1.0
+ * @Author whai文海
+ * @Date 2024/1/14 14:20
+ * @注释
+ */
+public class LeetCode203 {
+}

src/main/java/cn/whaifree/redo/redo_24_1_13/LeetCode209.java

@@ -0,0 +1,46 @@
+package cn.whaifree.redo.redo_24_1_13;
+
+import org.junit.Test;
+
+import java.util.Arrays;
+
+/**
+ * @version 1.0
+ * @Author whai文海
+ * @Date 2024/1/13 16:25
+ * @注释
+ */
+public class LeetCode209 {
+
+    @Test
+    public void test() {
+        System.out.println(new Solution().minSubArrayLen(41, new int[]{1,1,1,4,4}));
+    }
+
+    class Solution {
+        public int minSubArrayLen(int target, int[] nums) {
+
+            int left = 0;
+            int right = 0;
+            int minLength = Integer.MAX_VALUE;
+
+            int sum = 0;
+            do {
+                if (sum + nums[right] >= target) {
+                    if (right - left + 1 < minLength) {
+                        minLength = right - left + 1;
+                    }
+                    sum -= nums[left];
+                    left++;
+                } else {
+                    sum += nums[right];
+                    right++;
+                }
+
+            } while (right < nums.length); // 让右指针移动就好了
+
+            return minLength == Integer.MAX_VALUE ? 0 : minLength;
+        }
+
+    }
+}

src/main/java/cn/whaifree/redo/redo_24_1_13/LeetCode225.java

@@ -0,0 +1,73 @@
+package cn.whaifree.redo.redo_24_1_13;
+
+import org.junit.Test;
+
+import java.util.Deque;
+import java.util.LinkedList;
+
+/**
+ * @version 1.0
+ * @Author whai文海
+ * @Date 2024/1/13 13:36
+ * @注释
+ */
+public class LeetCode225 {
+
+    @Test
+    public void test() {
+        MyStack myStack = new MyStack();
+        myStack.push(1);
+        myStack.push(2);
+        myStack.push(3);
+        myStack.push(4);
+        myStack.push(5);
+        myStack.push(6);
+        myStack.push(7);
+        myStack.push(8);
+        myStack.push(9);
+        myStack.push(10);
+        System.out.println(myStack.pop());
+        System.out.println(myStack.top());
+        System.out.println(myStack.pop());
+
+
+    }
+
+
+    class MyStack {
+
+        public Deque<Integer> queue = null;
+        public MyStack() {
+            queue = new LinkedList<Integer>();
+        }
+
+        public void push(int x) {
+            int size = queue.size();
+            queue.add(x);
+            for (int i = 0; i < size; i++) {
+                queue.add(queue.pop());
+            }
+        }
+
+        public int pop() {
+            return queue.pop();
+        }
+
+        public int top() {
+            return queue.peek();
+        }
+
+        public boolean empty() {
+            return queue.isEmpty();
+        }
+    }
+
+/**
+ * Your MyStack object will be instantiated and called as such:
+ * MyStack obj = new MyStack();
+ * obj.push(x);
+ * int param_2 = obj.pop();
+ * int param_3 = obj.top();
+ * boolean param_4 = obj.empty();
+ */
+}

src/main/java/cn/whaifree/redo/redo_24_1_13/LeetCode232.java

@@ -0,0 +1,70 @@
+package cn.whaifree.redo.redo_24_1_13;
+
+import org.junit.Test;
+
+import java.util.Deque;
+import java.util.LinkedList;
+
+/**
+ * @version 1.0
+ * @Author whai文海
+ * @Date 2024/1/13 13:48
+ * @注释
+ */
+public class LeetCode232 {
+
+    @Test
+    public void test() {
+        MyQueue myQueue = new MyQueue();
+        myQueue.push(1);
+        myQueue.push(2);
+        myQueue.push(3);
+        System.out.println(myQueue.peek());
+        System.out.println(myQueue.pop());
+        System.out.println(myQueue.peek());
+    }
+
+
+    class MyQueue {
+
+        Deque<Integer> stack1;
+        Deque<Integer> stack2;
+
+        public MyQueue() {
+            stack1 = new LinkedList<>();
+            stack2 = new LinkedList<>();
+        }
+
+        public void push(int x) {
+            // 全部弹出到另一个栈，再全部弹回去
+            while (!stack1.isEmpty()) {
+                stack2.push(stack1.pop());
+            }
+            stack1.push(x);
+            while (!stack2.isEmpty()) {
+                stack1.push(stack2.pop());
+            }
+        }
+
+        public int pop() {
+            return stack1.pop();
+        }
+
+        public int peek() {
+            return stack1.peek();
+        }
+
+        public boolean empty() {
+            return stack1.isEmpty();
+        }
+    }
+
+/**
+ * Your MyQueue object will be instantiated and called as such:
+ * MyQueue obj = new MyQueue();
+ * obj.push(x);
+ * int param_2 = obj.pop();
+ * int param_3 = obj.peek();
+ * boolean param_4 = obj.empty();
+ */
+}

src/main/java/cn/whaifree/redo/redo_24_1_13/LeetCode239_false.java

@@ -0,0 +1,70 @@
+package cn.whaifree.redo.redo_24_1_13;
+
+import org.junit.Test;
+
+import java.util.Deque;
+import java.util.LinkedList;
+
+/**
+ * @version 1.0
+ * @Author whai文海
+ * @Date 2024/1/13 13:58
+ * @注释
+ */
+public class LeetCode239_false {
+
+    @Test
+    public void test() {
+        Solution solution = new Solution();
+        int[] nums = new int[]{1, 3, -1, -3, 5, 3, 6, 7};
+        int k = 3;
+        int[] ints = solution.maxSlidingWindow(nums, k);
+        for (int anInt : ints) {
+            System.out.println(anInt);
+        }
+    }
+
+    class Solution {
+        public int[] maxSlidingWindow(int[] nums, int k) {
+
+
+            Deque<Integer> queue = new LinkedList<Integer>();
+            int length = nums.length;
+            int[] res = new int[length - k + 1];
+            // 从0-k-1遍历，找到最大值
+            // 存下标到res数组中
+
+            for (int i = 0; i < k; i++) {
+
+                while (!queue.isEmpty() && nums[i] > nums[queue.peekLast()]) {
+                    queue.removeLast();
+                }
+                queue.addLast(i);
+            }
+
+            // 遍历剩余的k-1 --- length-1
+            // 如果找到比当前优先队列首位大的下标，就加入队列
+            // 并且需要判断当前窗口是不是在正确的区间内
+
+            // 第一个元素必然是queue.peek对应的数值
+            res[0] = nums[queue.peek()];
+            for (int i = k; i < length; i++) {
+                while (!queue.isEmpty() && nums[i] > nums[queue.peekLast()]) {
+                    queue.removeLast();
+                }
+                queue.addLast(i);
+
+                if (queue.peek() <= i - k) {
+                    queue.removeFirst();
+                }
+                // 注入res
+                Integer peek = queue.peek();
+                res[i - k + 1] = nums[peek];
+
+            }
+
+            return res;
+
+        }
+    }
+}

src/main/java/cn/whaifree/redo/redo_24_1_13/LeetCode2487.java

@@ -0,0 +1,59 @@
+package cn.whaifree.redo.redo_24_1_13;
+
+import cn.whaifree.leetCode.model.ListNode;
+import org.junit.Test;
+
+/**
+ * @version 1.0
+ * @Author whai文海
+ * @Date 2024/1/14 12:24
+ * @注释
+ */
+public class LeetCode2487 {
+
+    @Test
+    public void test() {
+        ListNode head = ListNode.listNodeFromArray(new int[]{5, 2, 13, 1, 3, 8});
+        new Solution().removeNodes(head).printList();
+    }
+
+    class Solution {
+        public ListNode removeNodes(ListNode head) {
+            // 逆转
+            ListNode newHead = reverse(head);
+
+            // 移除左边有更小的节点
+            remove(newHead);
+
+            // 再逆转
+            return reverse(newHead);
+        }
+
+        public void remove(ListNode head) {
+            ListNode index = head;
+            ListNode targetNode = head;
+            while (index.next != null) {
+                if (index.next.val < targetNode.val) {
+                    index.next = index.next.next;
+                }else {
+                    index = index.next;
+                    targetNode = index;
+                }
+            }
+        }
+
+        public ListNode reverse(ListNode head) {
+
+            ListNode pre = null;
+            ListNode index = head;
+            while (index != null) {
+                ListNode tmp = index.next;
+                index.next = pre;
+                pre = index;
+                index = tmp;
+            }
+            return pre;
+        }
+    }
+
+}

src/main/java/cn/whaifree/redo/redo_24_1_13/LeetCode28.java

@@ -0,0 +1,33 @@
+package cn.whaifree.redo.redo_24_1_13;
+
+import org.junit.Test;
+
+/**
+ * @version 1.0
+ * @Author whai文海
+ * @Date 2024/1/14 11:26
+ * @注释
+ */
+public class LeetCode28 {
+
+    @Test
+    public void test() {
+        System.out.println(new Solution().strStr("leetcode", "leeto"));
+    }
+
+    class Solution {
+        public int strStr(String haystack, String needle) {
+
+            int length = needle.length();
+            int index = 0;
+            int giveLength = haystack.length();
+            while (index <= giveLength - length) {
+                if (haystack.substring(index, index + length).equals(needle)) {
+                    return index;
+                }
+                index++;
+            }
+            return -1;
+        }
+    }
+}

src/main/java/cn/whaifree/redo/redo_24_1_13/LeetCode287.java

@@ -0,0 +1,60 @@
+package cn.whaifree.redo.redo_24_1_13;
+
+import org.junit.Test;
+
+/**
+ * @version 1.0
+ * @Author whai文海
+ * @Date 2024/1/14 12:53
+ * @注释
+ */
+public class LeetCode287 {
+
+    @Test
+    public void test() {
+        System.out.println(new Solution().findDuplicate(new int[]{1, 3, 4, 2, 2}));
+    }
+
+
+    class Solution {
+
+        /**
+         * 寻找循环链表的入口
+         * 1 3 4 2 2
+         * 0 1 2 3 4
+         *
+         * 0--->1--->3--->2--->4--->2
+         *
+         *
+         *
+         * @param nums
+         * @return
+         */
+        public int findDuplicate(int[] nums) {
+
+            // 快慢指针
+            int fast = 0;
+            int slow = 0;
+
+
+            // 找到相遇点
+            do {
+                fast = nums[nums[fast]];
+                slow = nums[slow];
+            }
+            while (fast != slow);
+
+            fast =0;
+            while (fast != slow) {
+                fast = nums[fast];
+                slow = nums[slow];
+            }
+            // 快指针指向头部，两个指针同志向前，直到相遇
+
+            return fast;
+        }
+
+    }
+
+
+}

src/main/java/cn/whaifree/redo/redo_24_1_13/LeetCode347.java

@@ -0,0 +1,110 @@
+package cn.whaifree.redo.redo_24_1_13;
+
+import org.junit.Test;
+
+import java.util.Comparator;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.PriorityQueue;
+
+/**
+ * @version 1.0
+ * @Author whai文海
+ * @Date 2024/1/13 15:10
+ * @注释
+ */
+public class LeetCode347 {
+
+    @Test
+    public void test() {
+        int[] x = new Solution1().topKFrequent(new int[]{2, 2, 1, 1, 1, 1, 1, 4, 4, 4, 4, 5, 5, 5, 3, 3, 3, 3, 3, 3}, 2);
+
+        for (int i : x) {
+            System.out.println(i);
+        }
+    }
+
+    class Solution {
+
+        public int[] topKFrequent(int[] nums, int k) {
+            // 统计频率
+            HashMap<Integer, Integer> map = new HashMap<>();
+            for (int i = 0; i < nums.length; i++) {
+                if (map.containsKey(nums[i])) {
+                    map.put(nums[i], map.get(nums[i]) + 1);
+                } else {
+                    map.put(nums[i], 1);
+                }
+            }
+
+            // 大顶堆
+            PriorityQueue<Integer> priorityQueue = new PriorityQueue<>(
+                    new Comparator<Integer>() {
+                        @Override
+                        public int compare(Integer o1, Integer o2) {
+                            return map.get(o2) - map.get(o1);
+                        }
+                    }
+            );
+
+
+            for (Map.Entry<Integer, Integer> entry : map.entrySet()) {
+                priorityQueue.add(entry.getKey());
+            }
+
+            int[] ints = new int[k];
+            for (int i = 0; i < k; i++) {
+                ints[i] = priorityQueue.poll();
+            }
+
+            return ints;
+        }
+
+    }
+
+    class Solution1 {
+
+        public int[] topKFrequent(int[] nums, int k) {
+            // 统计频率
+            HashMap<Integer, Integer> map = new HashMap<>();
+            for (int i = 0; i < nums.length; i++) {
+                if (map.containsKey(nums[i])) {
+                    map.put(nums[i], map.get(nums[i]) + 1);
+                } else {
+                    map.put(nums[i], 1);
+                }
+            }
+
+            // 小顶堆
+            PriorityQueue<Integer> priorityQueue = new PriorityQueue<>(
+                    new Comparator<Integer>() {
+                        @Override
+                        public int compare(Integer o1, Integer o2) {
+                            return map.get(o1) - map.get(o2);
+                        }
+                    }
+            );
+
+
+            for (Map.Entry<Integer, Integer> entry : map.entrySet()) {
+                // 导入前k个形成初始堆
+                if (priorityQueue.size() < k) {
+                    priorityQueue.add(entry.getKey());
+                } else if (map.get(entry.getKey()) > map.get(priorityQueue.peek())) {
+                    // 如果 该元素的频率比最小的值都大，则插入，并且删除最小值
+                    priorityQueue.remove();
+                    priorityQueue.add(entry.getKey());
+                }
+
+            }
+
+            int[] ints = new int[k];
+            for (int i = 0; i < k; i++) {
+                ints[i] = priorityQueue.poll();
+            }
+
+            return ints;
+        }
+
+    }
+}