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更新 LCR155.java、LeetCode207.java、LeetCode210.java 和 LeetCode583.java 文件，进行代码优化和逻辑调整。

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whaifree 2024-09-16 10:20:05 +08:00
parent 1e4aa82952
commit a75259b346
4 changed files with 255 additions and 1 deletions
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2
src/main/java/cn/whaifree/leetCode/LinkedList/LCR155.java → src/main/java/cn/whaifree/LCR/LCR155.java
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@ -1,4 +1,4 @@
package cn.whaifree.leetCode.LinkedList;
package cn.whaifree.LCR;
import org.junit.Test;

100
src/main/java/cn/whaifree/leetCode/Graph/LeetCode207.java Normal file
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package cn.whaifree.leetCode.Graph;
import org.junit.Test;
import java.util.*;
/**
* @version 1.0
* @Author whai文海
* @Date 2024/9/16 0:02
* @注释
*/
public class LeetCode207 {
@Test
public void test() {
int numCourses = 4;
int[][] prerequisites = {{1, 0},{0,2},{1,3}};
System.out.println(new Solution().canFinish(numCourses, prerequisites));
}
class Solution {
public boolean canFinish(int numCourses, int[][] prerequisites) {
List<List<Integer>> graph = new ArrayList<>();
for (int i = 0; i < numCourses; i++) {
graph.add(new ArrayList<>());
}
// 统计入度个数
int[] inGre = new int[numCourses];
for (int i = 0; i < prerequisites.length; i++) {
int course = prerequisites[i][0];
int preCourse = prerequisites[i][1];
graph.get(preCourse).add(course);
inGre[course]++;
}
// 对所有入度为0的进入队列
Deque<Integer> queue = new ArrayDeque<>();
for (int i = 0; i < numCourses; i++) {
if (inGre[i] == 0) {
queue.add(i);
}
}
// 出对，并去边
int exeCount = 0;
while (!queue.isEmpty()) {
Integer pop = queue.pop();
exeCount++;
// 遍历这个pop点的出边
List<Integer> popOut = graph.get(pop);
for (int i = 0; i < popOut.size(); i++) {
int deleteSideNode = popOut.get(i);
inGre[deleteSideNode]--;
if (inGre[deleteSideNode] == 0) {
queue.add(deleteSideNode);
}
}
}
// 如果队列中没有元素了，但还有边，返回false
return exeCount == numCourses;
}
}
class Solution1 {
public boolean canFinish(int numCourses, int[][] prerequisites) {
// 统计入度个数
int[] map = new int[2000];
for (int i = 0; i < prerequisites.length; i++) {
map[prerequisites[i][0]]++;
}
// 对所有入度为0的进入队列
Deque<Integer> queue = new ArrayDeque<>();
for (int i = 0; i < numCourses; i++) {
if (map[i] == 0) {
queue.add(i);
}
}
// 出对，并去边
int exeCount = 0;
while (!queue.isEmpty()) {
Integer pop = queue.pop();
exeCount++;
// 遍历所有的边
for (int i = 0; i < prerequisites.length; i++) {
if (prerequisites[i][1] == pop) {
int deleteSideNode = prerequisites[i][0];
map[deleteSideNode]--;
if (map[deleteSideNode] == 0) {
queue.add(deleteSideNode);
}
}
}
}
// 如果队列中没有元素了，但还有边，返回false
return exeCount == numCourses;
}
}
}

98
src/main/java/cn/whaifree/leetCode/Graph/LeetCode210.java Normal file
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package cn.whaifree.leetCode.Graph;
import org.junit.Test;
import java.util.*;
/**
* @version 1.0
* @Author whai文海
* @Date 2024/9/16 0:44
* @注释
*/
public class LeetCode210 {
@Test
public void test() {
int[][] prerequisites = {{1,0},{2,0},{3,1},{3,2}};
int[] res = new Solution().findOrder(4, prerequisites);
System.out.println(Arrays.toString(res));
}
public int[] findOrder(int numCourses, int[][] prerequisites) {
if (numCourses == 0) return new int[0];
int[] inDegrees = new int[numCourses];
// 建立入度表
for (int[] p : prerequisites) {
inDegrees[p[0]]++; // 记录每个节点的入度
}
// 入度为0的节点队列
Queue<Integer> queue = new LinkedList<>();
for (int i = 0; i < inDegrees.length; i++) {
if (inDegrees[i] == 0) queue.offer(i); // 入度为 0 的节点可以进行执行
}
int count = 0; // 记录可以执行的任务数
int[] res = new int[numCourses]; // 完整拓扑排序的执行过程
// 根据提供的可以执行的任务（入度为 0），删除入度为 0 的节点
while (!queue.isEmpty()){
int curr = queue.poll(); // 拿到一个可以执行的任务
res[count++] = curr; // 这个任务可以执行，作为下一次执行的节点
for (int[] p : prerequisites) {
if (p[1] == curr){ // {a,b} 表示 a 依赖 b b-->a
inDegrees[p[0]]--;
if (inDegrees[p[0]] == 0) queue.offer(p[0]);
}
}
}
if (count == numCourses) return res;
return new int[0];
}
class Solution {
public int[] findOrder(int numCourses, int[][] prerequisites) {
List<List<Integer>> graph = new ArrayList<>();
for (int i = 0; i < numCourses; i++) {
graph.add(new ArrayList<>());
}
int[] inGre = new int[numCourses];
Deque<Integer> deque = new LinkedList<>();
for (int[] prerequisite : prerequisites) {
int course = prerequisite[0];
int pre = prerequisite[1];
inGre[course]++;
graph.get(pre).add(course);
}
for (int i = 0; i < inGre.length; i++) {
if (inGre[i] == 0) {
deque.add(i);
}
}
int exec = 0;
int[] res = new int[numCourses];
while (!deque.isEmpty()) {
Integer exe = deque.pop();
res[exec] = exe;
exec++;
List<Integer> in = graph.get(exe);
for (int into = 0; into < in.size(); into++) {
Integer intoNode = in.get(into);
inGre[intoNode]--;
if (inGre[intoNode] == 0) {
deque.add(intoNode);
}
}
}
if (numCourses == exec) {
return res;
}
return new int[0];
}
}
}

56
src/main/java/cn/whaifree/redo/redo_all_240721/LeetCode583.java Normal file
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package cn.whaifree.redo.redo_all_240721;
import org.junit.Test;
/**
* @version 1.0
* @Author whai文海
* @Date 2024/9/16 1:01
* @注释
*/
public class LeetCode583 {
@Test
public void test() {
String word1 = "leetcode";
String word2 = "etco";
System.out.println(new Solution().minDistance(word1, word2));
}
class Solution {
public int minDistance(String word1, String word2) {
char[] w1 = word1.toCharArray();
char[] w2 = word2.toCharArray();
int[][] dp = new int[w1.length + 1][w2.length + 1];
for (int i = 0; i <= w2.length; i++) {
dp[0][i] = i;
}
for (int j = 0; j <= w1.length; j++) {
dp[j][0] = j;
}
/**
* '' s e a
* '' 0 1 2 3
* e 1 2 1 2 不配 左边|上 +1 配 对i-1 j-1
* a 2 3 2
* t 3
*
* @param word1
* @param word2
* @return
*/
for (int i = 0; i < w1.length; i++) {
for (int j = 0; j < w2.length; j++) {
if (w1[i] == w2[j]) {
dp[i + 1][j + 1] = dp[i][j];
}else {
dp[i + 1][j + 1] = Math.min(dp[i][j + 1], dp[i + 1][j]) + 1;
}
}
}
return dp[w1.length][w2.length];
}
}
}