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leecode更新

This commit is contained in:
markilue 2023-05-12 13:01:42 +08:00
parent 015e83793d
commit cf862785bf
5 changed files with 234 additions and 2 deletions
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41
Leecode/src/main/java/com/markilue/leecode/hot100/interviewHot/listnode/LC_143_ReorderList.java Normal file
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@ -0,0 +1,41 @@
package com.markilue.leecode.hot100.interviewHot.listnode;
import com.markilue.leecode.listnode.ListNode;
/**
*@BelongsProject: Leecode
*@BelongsPackage: com.markilue.leecode.hot100.interviewHot.listnode
*@Author: markilue
*@CreateTime: 2023-05-12 10:49
*@Description: TODO 力扣143 重排链表:
*@Version: 1.0
*/
public class LC_143_ReorderList {
ListNode p;
//重复模式:寻找不变操作进行递归
public void reorderList(ListNode head) {
p = head;
recur(head);
}
public void recur(ListNode cur) {
if (cur == null) {
return;
}
recur(cur.next);//深度优先直接找到最后面的
if (p.next == null || p == cur || cur.next == p) {
//遍历到中间了,不需要继续遍历了
p.next = null;
return;
}
//处理当前节点的逻辑
cur.next = p.next;
p.next = cur;
p = p.next.next;//移动到下一个需要操作的位置
}
}

60
Leecode/src/main/java/com/markilue/leecode/hot100/interviewHot/listnode/LC_25_ReverseKGroup.java Normal file
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@ -0,0 +1,60 @@
package com.markilue.leecode.hot100.interviewHot.listnode;
import com.markilue.leecode.listnode.ListNode;
import com.markilue.leecode.listnode.ListNodeUtils;
import org.junit.Test;
/**
*@BelongsProject: Leecode
*@BelongsPackage: com.markilue.leecode.hot100.interviewHot.listnode
*@Author: markilue
*@CreateTime: 2023-05-12 11:05
*@Description: TODO 力扣25 K个一组翻转链表
*@Version: 1.0
*/
public class LC_25_ReverseKGroup {
@Test
public void test() {
ListNode root = ListNodeUtils.build(new int[]{1, 2, 3, 4, 5});
ListNodeUtils.print(reverseKGroup(root,2));
}
//寻找循环不变量:本质上就是四个一组的操作，考虑使用递归
public ListNode reverseKGroup(ListNode head, int k) {
//k个一组，至少要保证head之后有k个
ListNode temp = head;
for (int i = 0; i < k; i++) {
if (temp == null) return head;//没有k个不做任何处理
temp = temp.next;
}
//有k个,开始翻转这K个
ListNode root = reverseNode(head, temp);
//因为调用了reverseNode,从这里开始head变成了k个一组中的最后一个了,所以后续翻转的拼到head后面
head.next = reverseKGroup(temp, k);//翻转temp后面的
return root;
}
public ListNode reverseNode(ListNode start, ListNode end) {
//反转部分链表
if (start == null) return start;
ListNode fake = new ListNode();
ListNode temp =start;
ListNode tempNext;
while (temp != end) {
tempNext = temp.next;
temp.next = fake.next;
fake.next = temp;
temp = tempNext;
}
return fake.next;
}
}

24
Leecode/src/main/java/com/markilue/leecode/hot100/interviewHot/listnode/LC_84_DeleteDuplicatesII.java → Leecode/src/main/java/com/markilue/leecode/hot100/interviewHot/listnode/LC_82_DeleteDuplicatesII.java
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@ -10,7 +10,7 @@ import com.markilue.leecode.listnode.ListNode;
*@Description: TODO 力扣82 删除排序链表中的重复元素II:重复全删
*@Version: 1.0
*/
public class LC_84_DeleteDuplicatesII {
public class LC_82_DeleteDuplicatesII {
public ListNode deleteDuplicates(ListNode head) {
ListNode fake = new ListNode(-101);
@ -30,4 +30,26 @@ public class LC_84_DeleteDuplicatesII {
}
return fake.next;
}
//二刷
public ListNode deleteDuplicates1(ListNode head) {
ListNode fake = new ListNode(-101);
fake.next = head;
ListNode cur = fake;
while (cur.next != null && cur.next.next != null) {
if (cur.next.val == cur.next.next.val) {
ListNode temp = cur.next;
while (temp.next != null && temp.val == temp.next.val) {
temp = temp.next;
}
cur.next = temp.next;
} else {
cur = cur.next;
}
}
return fake.next;
}
}

50
Leecode/src/main/java/com/markilue/leecode/hot100/interviewHot/window/LC_76_MinWindow.java
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@ -25,7 +25,7 @@ public class LC_76_MinWindow {
@Test
public void test1() {
String s = "ADOBECODEBANC", t = "ABC";
System.out.println(minWindow2(s, t));
System.out.println(minWindow4(s, t));
}
@ -229,5 +229,53 @@ public class LC_76_MinWindow {
return len == Integer.MAX_VALUE ? "" : s.substring(start, start + len);
}
//三刷
public String minWindow4(String s, String t) {
//构造合适窗口
HashMap<Character, Integer> need = new HashMap<>();
for (int i = 0; i < t.length(); i++) {
char c = t.charAt(i);
need.put(c, need.getOrDefault(c, 0) + 1);
}
HashMap<Character, Integer> window = new HashMap<>();
int left = 0;
int right = 0;
int start = 0;
int len = Integer.MAX_VALUE;
int size = need.size();
while (right < s.length()) {
char c = s.charAt(right++);
if (need.containsKey(c)) {
window.put(c, window.getOrDefault(c, 0) + 1);
if (window.get(c).equals(need.get(c))) {
size--;
}
}
while (size == 0 && left < right) {
//开始缩小窗口
int cur = right - left;//因为之前right+1了所以这里不用+
if (cur < len) {
len = cur;
start = left;
}
char c1 = s.charAt(left++);
if (need.containsKey(c1)) {
Integer num = window.get(c1);
if (num.equals(need.get(c1))) {
size++;
}
window.put(c1, num - 1);
}
}
}
return len == Integer.MAX_VALUE ? "" : s.substring(start, start + len);
}
}

61
Leecode/src/main/java/com/markilue/leecode/hot100/second/T57_142_MaxProduct.java Normal file
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@ -0,0 +1,61 @@
package com.markilue.leecode.hot100.second;
import org.junit.Test;
/**
*@BelongsProject: Leecode
*@BelongsPackage: com.markilue.leecode.hot100.second
*@Author: markilue
*@CreateTime: 2023-05-12 11:31
*@Description: TODO 力扣152 乘积最大子数组
*@Version: 1.0
*/
public class T57_142_MaxProduct {
@Test
public void test() {
int[] nums = {2, 3, -2, 4};
System.out.println(maxProduct(nums));
}
//由于是乘积:且数组有正有负，所以最小的也可以变成最大的，最大的也可以变成最小的
public int maxProduct(int[] nums) {
int[][] dp = new int[nums.length][2];//<min,max>
dp[0][0] = nums[0];
dp[0][1] = nums[0];
int max = nums[0];
for (int i = 1; i < nums.length; i++) {
//当前位置,一定是要了当前的数的，通过max来中间的过程
dp[i][0] = Math.min(Math.min(nums[i], dp[i - 1][0] * nums[i]), dp[i - 1][1] * nums[i]);
dp[i][1] = Math.max(Math.max(nums[i], dp[i - 1][0] * nums[i]), dp[i - 1][1] * nums[i]);
if (max < dp[i][1]) {
max = dp[i][1];
}
}
return max;
}
//滚动数组优化
public int maxProduct1(int[] nums) {
int dp0 = nums[0];
int dp1 = nums[0];
int max = nums[0];
int temp;
for (int i = 1; i < nums.length; i++) {
//当前位置,一定是要了当前的数的，通过max来中间的过程
temp = dp0;
dp0 = Math.min(Math.min(nums[i], dp0 * nums[i]), dp1 * nums[i]);
dp1 = Math.max(Math.max(nums[i], temp* nums[i]), dp1 * nums[i]);
if (max < dp1) {
max = dp1;
}
}
return max;
}
}