#feat:leetcode p1115题题解

src/leetcode/p1115/FooBar.java

@@ -0,0 +1,81 @@
+package leetcode.p1115;
+
+import java.util.concurrent.Semaphore;
+import java.util.concurrent.locks.Condition;
+import java.util.concurrent.locks.ReentrantLock;
+
+/**
+ * @ProjectName: LeetCode
+ * @FileName: FooBar
+ * @Author: 杨逸
+ * @Data:2026/3/25 21:11
+ * @Description: https://leetcode.cn/problems/print-foobar-alternately/
+ * 1115. 交替打印 FooBar
+ */
+public class FooBar {
+    private int n;
+    private volatile boolean fooFlag = true;
+    private final ReentrantLock lock;
+    private final Condition condition;
+    public FooBar(int n) {
+        this.n = n;
+        lock = new ReentrantLock();
+        condition = lock.newCondition();
+    }
+
+    public void foo(Runnable printFoo) throws InterruptedException {
+        for (int i = 0; i < n; i++) {
+            lock.lock();
+            try {
+                while (!fooFlag)condition.await();
+                printFoo.run();
+                fooFlag = !fooFlag;
+                condition.signalAll();
+            } finally {
+                lock.unlock();
+            }
+        }
+    }
+
+    public void bar(Runnable printBar) throws InterruptedException {
+        for (int i = 0; i < n; i++) {
+            lock.lock();
+            try {
+                while (fooFlag)condition.await();
+                printBar.run();
+                fooFlag = !fooFlag;
+                condition.signalAll();
+            } finally {
+                lock.unlock();
+            }
+        }
+    }
+}
+class SemaphoreSolution{
+    private int n;
+    private final Semaphore semaphore1 = new Semaphore(1);
+    private final Semaphore semaphore2 = new Semaphore(0);
+    public SemaphoreSolution(int n) {
+        this.n = n;
+    }
+
+    public void foo(Runnable printFoo) throws InterruptedException {
+
+        for (int i = 0; i < n; i++) {
+            semaphore1.acquire();
+            // printFoo.run() outputs "foo". Do not change or remove this line.
+            printFoo.run();
+            semaphore2.release();
+        }
+    }
+
+    public void bar(Runnable printBar) throws InterruptedException {
+
+        for (int i = 0; i < n; i++) {
+            semaphore2.acquire();
+            // printBar.run() outputs "bar". Do not change or remove this line.
+            printBar.run();
+            semaphore1.release();
+        }
+    }
+}