redo

src/main/java/cn/whaifree/leetCode/StaticObjTest.java

@@ -0,0 +1,21 @@
+package cn.whaifree.leetCode;
+
+public class StaticObjTest {
+    static class Test{
+        // 静态变量存方法区
+        static ObjectHolder staticObj = new ObjectHolder();
+        // 成员变量存堆中
+        ObjectHolder instanceObj = new ObjectHolder();
+
+        void foo(){
+            // 变量名存放在foo()方法中的栈帧中的局部变量表中
+            ObjectHolder localObj = new ObjectHolder();
+            System.out.println("done");
+        }
+    }
+
+
+    private static class ObjectHolder{
+
+    }
+}

src/main/java/cn/whaifree/leetCode/T.java

@@ -1,130 +0,0 @@
-package cn.whaifree.leetCode;
-
-import java.util.ArrayList;
-import java.util.Random;
-
-/**
- * @version 1.0
- * @Author whai文海
- * @Date 2024/2/27 17:58
- * @注释
- */
-public class T {
-
-    public int A() {
-        B();
-        return 1;
-    }
-
-    public void B() {
-
-    }
-}
-
-interface Animal {
-    void eat();
-}
-
-class Hunter{
-   void hunt() {
-
-   }
-}
-
-class Cat extends Hunter implements Animal {
-
-    @Override
-    void hunt() {
-        System.out.println("cat hunt");
-    }
-
-    @Override
-    public void eat() {
-        System.out.println("cat eat");
-    }
-}
-
-class Dog extends Hunter implements Animal {
-
-    public Dog() {
-        super();
-    }
-
-    public Dog(String name) {
-        super();
-    }
-
-    @Override
-    void hunt() {
-        System.out.println("dog hunt");
-    }
-
-    @Override
-    public void eat() {
-        System.out.println("dog eat");
-    }
-}
-
-class AnimalTest {
-    public static void main(String[] args) {
-        // 晚期绑定，动态链接
-        // 运行时才能确定
-        Animal animal = new Cat();
-        animal.eat();
-        Hunter hunter = (Hunter) animal;
-        hunter.hunt();
-
-        // 静态多态
-        Dog dog = new Dog("!23");
-
-
-    }
-}
-
-
-class Father{
-    public static void print(String str){
-        System. out. println("father "+str);
-    }
-    public void show(String str){
-        System. out. println("father"+str);
-    }
-}
-
-class Son extends Father {
-
-
-}
-
-class VirtualMethodTest {
-    public static void main(String[] args) {
-        Son.print("coder");
-        Father fa = new Father();
-        fa.show("a");
-    }
-}
-
-
-
-class Picture{
-    int number = 0;
-    public Picture() {
-
-    }
-
-    public Picture(int number) {
-        this.number = number;
-    }
-
-    public static void main(String[]args){
-        ArrayList<Picture> list = new ArrayList<>();
-        while(true){
-            try {
-                Thread.sleep(10);
-            } catch (InterruptedException e){
-                e.printStackTrace();
-            }
-            list.add(new Picture(new Random().nextInt(1024*1024)));
-        }
-    }
-}

src/main/java/cn/whaifree/redo/redo_24_3_1/LeetCode1005.java

@@ -0,0 +1,77 @@
+package cn.whaifree.redo.redo_24_3_1;
+
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Comparator;
+import java.util.function.ToIntFunction;
+
+/**
+ * @version 1.0
+ * @Author whai文海
+ * @Date 2024/3/2 11:40
+ * @注释
+ */
+public class LeetCode1005 {
+
+    @Test
+    public void test() {
+        int[] nums = new int[]{5,6,9,-3,3};
+        int k =2;
+        int res = new Solution1().largestSumAfterKNegations(nums, k);
+        System.out.println(res);
+    }
+
+    class Solution {
+        public int largestSumAfterKNegations(int[] nums, int k) {
+            // 从小到大排序，把前面的负数替换后，如果k是否有剩余
+            Arrays.sort(nums);
+            int sum = 0;
+            int minInNums = Integer.MAX_VALUE;
+            for (int i = 0; i < nums.length; i++) {
+                if (nums[i] < 0 && k > 0) {
+                    nums[i] = -nums[i];
+                    k--;
+                }
+                minInNums = Math.min(minInNums, nums[i]);
+                sum += nums[i];
+            }
+
+            if ((k % 2 == 1 )) {
+                sum = sum - minInNums - minInNums;
+            }
+            return sum;
+
+        }
+    }
+
+    class Solution1 {
+        public int largestSumAfterKNegations(int[] nums, int k) {
+            // 按照绝对值排序
+            nums = Arrays.stream(nums).boxed().sorted(new Comparator<Integer>() {
+                @Override
+                public int compare(Integer o1, Integer o2) {
+                    return Math.abs(o2) - Math.abs(o1);
+                }
+            }).mapToInt(Integer::intValue).toArray();
+
+
+            int sum = 0;
+            // 9 -8 -7 6 4 3
+            for (int i = 0; i < nums.length; i++) {
+                if (nums[i] < 0 && k > 0) {
+                    nums[i] = -nums[i];
+                    k--;
+                }
+                sum += nums[i];
+            }
+
+            if (k % 2 == 1 ) {
+                sum -= nums[nums.length - 1] + nums[nums.length - 1];
+            }
+            return sum;
+
+        }
+    }
+}

src/main/java/cn/whaifree/redo/redo_24_3_1/LeetCode134.java

@@ -10,6 +10,11 @@ import org.junit.Test;
  */
 public class LeetCode134 {
 
+
+    public static void main(String[] args) {
+        
+    }
+
     @Test
     public void test() {
         System.out.println(new Solution().canCompleteCircuit(new int[]{1, 2, 3, 4, 5}, new int[]{3, 4, 5, 1, 2}));

src/main/java/cn/whaifree/redo/redo_24_3_1/LeetCode135.java

@@ -0,0 +1,49 @@
+package cn.whaifree.redo.redo_24_3_1;
+
+import org.junit.Test;
+
+import java.util.Arrays;
+
+/**
+ * @version 1.0
+ * @Author whai文海
+ * @Date 2024/3/3 12:16
+ * @注释
+ */
+public class LeetCode135 {
+
+    @Test
+    public void test() {
+        new Solution().candy(new int[]{1, 0, 2, 4, 1});
+    }
+
+    class Solution {
+        public int candy(int[] ratings) {
+            // 从前往后，如果rating高，就+1糖果
+            int[] distribute = new int[ratings.length];
+
+            distribute[0] = 1;
+            for (int i = 1; i < ratings.length; i++) {
+
+                if (distribute[i]==0) distribute[i] = 1;
+                if (ratings[i] > ratings[i - 1]) {
+                    distribute[i] = distribute[i - 1] + 1;
+                }
+            }
+
+            for (int i = distribute.length - 1; i > 0; i--) {
+                // 需要同时满足 比两边都高
+                if (ratings[i - 1] > ratings[i]) {
+                    distribute[i - 1] = Math.max(distribute[i - 1], distribute[i] + 1);
+                }
+            }
+
+            int sum = 0;
+            for (int i : distribute) {
+                sum += i;
+            }
+            return sum;
+        }
+
+    }
+}

src/main/java/cn/whaifree/redo/redo_24_3_1/LeetCode406.java

@@ -0,0 +1,80 @@
+package cn.whaifree.redo.redo_24_3_1;
+
+import org.junit.Test;
+
+import java.util.Arrays;
+import java.util.Comparator;
+import java.util.LinkedList;
+
+/**
+ * @version 1.0
+ * @Author whai文海
+ * @Date 2024/3/3 12:30
+ * @注释
+ */
+public class LeetCode406 {
+
+
+
+
+    @Test
+    public void test() {
+        String a = "d";
+        String b = "d";
+        System.out.println(a == b);
+        a = new String("d");
+        System.out.println("a=" + a);
+        System.out.println("b=" + b);
+        System.out.println(a == b);
+
+        new Solution().reconstructQueue(
+                new int[][]{{7, 0}, {4, 4}, {7, 1}, {5, 0}, {6, 1}, {5, 2}}
+        );
+    }
+
+    class Solution {
+        public int[][] reconstructQueue(int[][] people) {
+
+            LinkedList<int[]> e = new LinkedList<>();
+            // 1. 安升高先排序，同身高k多的放后面
+            Arrays.sort(people, new Comparator<int[]>() {
+                @Override
+                public int compare(int[] o1, int[] o2) {
+                    if (o1[0] == o2[0]) {
+                        return o1[1] - o2[1];
+                    }else {
+                        return o2[0] - o1[0];
+                    }
+                }
+            });
+
+
+            for (int[] person : people) {
+                e.add(person[1], person);
+            }
+
+
+            return e.toArray(new int[people.length][]);
+        }
+    }
+
+}
+
+
+class StringExer{
+    String str = new String("good");
+    char[] chars = {'a', 'b', 'c', 'd'};
+
+    public void change(String str, char[] chars) {
+        str = "bad";
+        chars[0] = 'e';
+    }
+
+    public static void main(String[] args) {
+        StringExer stringExer = new StringExer();
+        stringExer.change(stringExer.str, stringExer.chars);
+        System.out.println(stringExer.str);
+        System.out.println(stringExer.chars);
+    }
+
+}

src/main/java/cn/whaifree/redo/redo_24_3_1/LeetCode491.java

@@ -0,0 +1,56 @@
+package cn.whaifree.redo.redo_24_3_1;
+
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.LinkedList;
+import java.util.List;
+
+/**
+ * @version 1.0
+ * @Author whai文海
+ * @Date 2024/3/3 19:40
+ * @注释
+ */
+public class LeetCode491 {
+
+    @Test
+    public void test() {
+        for (List<Integer> subsequence : new Solution().findSubsequences(new int[]{4,4,3,2,1})) {
+            System.out.println(subsequence);
+        }
+    }
+
+    class Solution {
+        List<List<Integer>> res = new ArrayList<>();
+        LinkedList<Integer> path = new LinkedList<>();
+
+        public List<List<Integer>> findSubsequences(int[] nums) {
+            backTracking(nums, 0);
+            return res;
+        }
+
+        public void backTracking(int[] nums, int start) {
+            if (path.size() >= 2) {
+                res.add(new LinkedList<>(path));
+            }
+            if (start >= nums.length) {
+                return;
+            }
+
+            HashSet<Integer> set = new HashSet<>();
+            for (int i = start; i < nums.length; i++) {
+
+                if ((path.isEmpty() || path.getLast() <= nums[i]) && !set.contains(nums[i])) {
+                    path.add(nums[i]);
+                    set.add(nums[i]);
+                    backTracking(nums, i + 1);
+                    path.removeLast();
+                }
+            }
+
+        }
+    }
+
+}

src/main/java/cn/whaifree/redo/redo_24_3_1/LeetCode51.java

@@ -1,6 +1,6 @@
 package cn.whaifree.redo.redo_24_3_1;
 
-import cn.whaifree.leetCode.T;
+
 import org.junit.Test;
 
 import java.util.ArrayList;

src/main/java/cn/whaifree/redo/redo_24_3_1/LeetCode860.java

@@ -0,0 +1,45 @@
+package cn.whaifree.redo.redo_24_3_1;
+
+import org.junit.Test;
+
+/**
+ * @version 1.0
+ * @Author whai文海
+ * @Date 2024/3/3 11:57
+ * @注释
+ */
+public class LeetCode860 {
+
+    @Test
+    public void test() {
+        System.out.println(new Solution().lemonadeChange(new int[]{5,5,10,10,20}));
+    }
+
+    class Solution {
+        public boolean lemonadeChange(int[] bills) {
+
+            int haveFive = 0;
+            int haveTen = 0;
+            for (int bill : bills) {
+                if (bill == 5) {
+                    haveFive++;
+                } else if (bill == 10) {
+                    haveTen++;
+                    haveFive--;
+                } else if (bill == 20) {
+                    if (haveTen >= 1) {
+                        haveTen--;
+                        haveFive--;
+                    }else {
+                        haveFive -= 3;
+                    }
+                }
+                if (haveFive < 0 || haveTen < 0) {
+                    return false;
+                }
+            }
+            return true;
+
+        }
+    }
+}