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leecode，rt_phm更新更新

This commit is contained in:
kevinding1125 2023-05-30 19:34:16 +08:00
parent af7485f4af
commit db735dbbc3
4 changed files with 284 additions and 1 deletions
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99
Leecode/src/main/java/com/markilue/leecode/hot100/interviewHot/union_find/LC_685_FindRedundantConnection.java
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@ -2,6 +2,7 @@ package com.markilue.leecode.hot100.interviewHot.union_find;
import org.junit.Test;
import java.util.ArrayList;
import java.util.Arrays;
/**
@ -14,9 +15,105 @@ import java.util.Arrays;
*/
public class LC_685_FindRedundantConnection {
public int[] findRedundantDirectedConnection(int[][] edges) {
int[] father;
int n;
private void init(int[] father) {
for (int i = 0; i < father.length; i++) {
father[i] = i;
}
}
private int find(int u) {
if (father[u] == u) {
return u;
}
father[u] = find(father[u]);
return father[u];
}
private void join(int u, int v) {
u = find(u);
v = find(v);
if (u == v) return;
father[v] = u;
}
private boolean same(int u, int v) {
u = find(u);
v = find(v);
return u == v;
}
/**
* 在有向图里找到需要删除的那条边，删除之后会变为树结构
* @param edges
* @return
*/
private int[] getRemoveEdge(int[][] edges) {
init(father);
for (int[] edge : edges) {
if (same(edge[0], edge[1])) {
return edge;//有连接的
}
join(edge[0], edge[1]);
}
return null;
}
/**
* 删除一条边之后判断是不是树
* @param edges
* @param deleteEdge 要删除的边
* @return
*/
private boolean isTreeAfterRemoveEdge(int[][] edges, int deleteEdge) {
init(father);
for (int i = 0; i < edges.length; i++) {
//跳过删除的边,判断是否为树
if (deleteEdge == i) continue;
if (same(edges[i][0], edges[i][1])) {
return false;
}
join(edges[i][0], edges[i][1]);
}
return true;
}
public int[] findRedundantDirectedConnection(int[][] edges) {
n = 1010;
father = new int[n];
init(father);
//判断图的入度
int[] oneDegree = new int[n];
for (int[] edge : edges) {
oneDegree[edge[1]]++;
}
// 找入度为2的节点所对应的边，注意要倒序，因为优先返回最后出现在二维数组中的答案
ArrayList<Integer> twoDegree = new ArrayList<>();
for (int i = edges.length - 1; i >= 0; i--) {
if (oneDegree[edges[i][1]] == 2) {
twoDegree.add(i);
}
}
// 处理图中情况1 和 情况2
// 如果有入度为2的节点，那么一定是两条边里删一个，看删哪个可以构成树
if (!twoDegree.isEmpty()) {
if (isTreeAfterRemoveEdge(edges, twoDegree.get(0))) {
return edges[twoDegree.get(0)];
}
return edges[twoDegree.get(1)];
}
return getRemoveEdge(edges);
}
}

60
Leecode/src/main/java/com/markilue/leecode/hot100/second/T75_283_MoveZeroes.java Normal file
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@ -0,0 +1,60 @@
package com.markilue.leecode.hot100.second;
import org.junit.Test;
import java.util.Arrays;
/**
*@BelongsProject: Leecode
*@BelongsPackage: com.markilue.leecode.hot100.second
*@Author: markilue
*@CreateTime: 2023-05-30 17:15
*@Description: TODO 力扣283 移动零:
*@Version: 1.0
*/
public class T75_283_MoveZeroes {
@Test
public void test() {
int[] nums = {0, 1, 0, 3, 12};
moveZeroes(nums);
System.out.println(Arrays.toString(nums));
}
//插入排序
public void moveZeroes(int[] nums) {
for (int i = nums.length - 1; i >= 0; i--) {
if (nums[i] == 0) {
//需要更换位置
int j = i;
while (j < nums.length - 1 && nums[j + 1] != 0) {
nums[j] = nums[j + 1];
j++;
}
nums[j] = 0;
}
}
}
//双指针
public void moveZeroes1(int[] nums) {
int left = 0;
int right = 0;//寻找不是0的 注意是从0开始不是从length开始
while (right < nums.length) {
if (nums[right] != 0) {
swap(nums, left, right);
left++;
}
right++;
}
}
private void swap(int[] nums, int left, int right) {
int temp = nums[left];
nums[left] = nums[right];
nums[right] = temp;
}
}

34
Leecode/src/main/java/com/markilue/leecode/hot100/second/T76_287_FindDuplicate.java Normal file
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@ -0,0 +1,34 @@
package com.markilue.leecode.hot100.second;
import org.junit.Test;
/**
*@BelongsProject: Leecode
*@BelongsPackage: com.markilue.leecode.hot100.second
*@Author: markilue
*@CreateTime: 2023-05-30 17:46
*@Description: TODO 力扣287 寻找重复数
*@Version: 1.0
*/
public class T76_287_FindDuplicate {
@Test
public void test() {
int[] nums = {1, 3, 4, 2, 2};
System.out.println(findDuplicate(nums));
}
//改变数组
public int findDuplicate(int[] nums) {
for (int i = 0; i < nums.length; i++) {
nums[nums[i] % nums.length] += nums.length;
}
for (int i = 0; i < nums.length; i++) {
if (nums[i] / nums.length > 1) {
return i;
}
}
return -1;
}
}

92
Leecode/src/main/java/com/markilue/leecode/hot100/second/T77_297_Codec.java Normal file
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@ -0,0 +1,92 @@
package com.markilue.leecode.hot100.second;
import com.markilue.leecode.tree.TreeNode;
import com.markilue.leecode.tree.TreeUtils;
import org.junit.Test;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
/**
*@BelongsProject: Leecode
*@BelongsPackage: com.markilue.leecode.hot100.second
*@Author: markilue
*@CreateTime: 2023-05-30 17:58
*@Description: TODO 力扣297 二叉树的序列化与反序列化
*@Version: 1.0
*/
public class T77_297_Codec {
@Test
public void test() {
List<Integer> nodeList = new ArrayList<>(Arrays.asList(1, 2, 3, null, null, 4, 5));
TreeNode root = TreeUtils.structureTree(nodeList, 0);
System.out.println(serialize(root));
TreeNode next = deserialize(serialize(root));
TreeUtils.printTreeByLevel(next);
// System.out.println(next);
}
// Encodes a tree to a single string.
public String serialize(TreeNode root) {
StringBuilder sb = new StringBuilder();
serialize(root, sb);
return sb.toString();
}
public void serialize(TreeNode node, StringBuilder sb) {
if (node == null) {
return;
}
sb.append(node.val);
if (node.left != null) {
sb.append("(");
serialize(node.left, sb);
sb.append(")");
}
if (node.right != null) {
if (node.left == null) {
sb.append("()");
}
sb.append("(");
serialize(node.right, sb);
sb.append(")");
}
}
int in = 0;
// Decodes your encoded data to tree.
public TreeNode deserialize(String data) {
if (in >= data.length() || data.charAt(in) == ')') {
return null;
}
TreeNode root = new TreeNode();
int multi = 1;
if (data.charAt(in) == '-') {
multi = -1;
in++;
}
while (in < data.length() && data.charAt(in) >= '0' && data.charAt(in) <= '9') {
root.val = root.val * 10 + data.charAt(in)-'0';
in++;
}
root.val *= multi;
if(in<data.length()&&data.charAt(in)=='('){
in++;//左括号
root.left = deserialize(data);
in++;//右括号
}
if(in<data.length()&&data.charAt(in)=='('){
in++;//左括号
root.right = deserialize(data);
in++;//右括号
}
return root;
}
}