leetcode: Simplify zero-even-odd

XuShaohua · Dec 5, 2023 · 61a7fca · 61a7fca
1 parent ed7bfe9
commit 61a7fca
Showing 1 changed file with 29 additions and 92 deletions.
diff --git a/leetcode/1116.print-zero-even-odd/src/with_condvar.rs b/leetcode/1116.print-zero-even-odd/src/with_condvar.rs
@@ -10,14 +10,8 @@ use std::thread;
 struct ZeroEvenOdd {
     n: i32,
 
-    zero_mutex: Mutex<bool>,
-    zero_cvar: Condvar,
-
-    even_mutex: Mutex<i32>,
-    even_cvar: Condvar,
-
-    odd_mutex: Mutex<i32>,
-    odd_cvar: Condvar,
+    mutex: Mutex<i32>,
+    cvar: Condvar,
 }
 
 fn print_number(_prefix: &str, x: i32) {
@@ -27,112 +21,55 @@ fn print_number(_prefix: &str, x: i32) {
 impl ZeroEvenOdd {
     pub fn new(n: i32) -> Self {
         Self {
-            n,
-
-            zero_mutex: Mutex::new(true),
-            zero_cvar: Condvar::new(),
-
-            even_mutex: Mutex::new(0),
-            even_cvar: Condvar::new(),
+            n: 2 * n,
 
-            odd_mutex: Mutex::new(0),
-            odd_cvar: Condvar::new(),
+            mutex: Mutex::new(1),
+            cvar: Condvar::new(),
         }
     }
 
     pub fn zero(&self) {
-        for i in 0..=self.n {
-            {
-                let mut zero_mutex = self.zero_mutex.lock().unwrap();
-                while !*zero_mutex {
-                    zero_mutex = self.zero_cvar.wait(zero_mutex).unwrap();
-                }
-                *zero_mutex = false;
+        loop {
+            let mut mutex = self.mutex.lock().unwrap();
+            while *mutex <= self.n && *mutex % 2 == 0 {
+                mutex = self.cvar.wait(mutex).unwrap();
             }
-            if i == self.n {
-                break;
+            if *mutex > self.n {
+                return;
             }
-
             print_number("zero", 0);
-
-            let next_num = i + 1;
-            if next_num % 2 == 0 {
-                let mut num_mutex = self.even_mutex.lock().unwrap();
-                *num_mutex = next_num;
-                self.even_cvar.notify_one();
-            } else {
-                let mut num_mutex = self.odd_mutex.lock().unwrap();
-                *num_mutex = next_num;
-                self.odd_cvar.notify_one();
-            }
-        }
-
-        {
-            let mut num_mutex = self.even_mutex.lock().unwrap();
-            *num_mutex = -1;
-            self.even_cvar.notify_one();
-        }
-        {
-            let mut num_mutex = self.odd_mutex.lock().unwrap();
-            *num_mutex = -1;
-            self.odd_cvar.notify_one();
+            *mutex += 1;
+            self.cvar.notify_all();
         }
     }
 
     pub fn even(&self) {
         loop {
-            let even_num;
-            {
-                let mut num_mutex = self.even_mutex.lock().unwrap();
-                loop {
-                    if *num_mutex == -1 {
-                        return;
-                    }
-                    if *num_mutex != 0 {
-                        break;
-                    }
-                    num_mutex = self.even_cvar.wait(num_mutex).unwrap();
-                }
-
-                even_num = *num_mutex;
-                *num_mutex = 0;
+            let mut mutex = self.mutex.lock().unwrap();
+            while *mutex <= self.n && (*mutex % 2 != 0 || *mutex % 4 != 0) {
+                mutex = self.cvar.wait(mutex).unwrap();
             }
-
-            print_number("even", even_num);
-            {
-                let mut zero_mutex = self.zero_mutex.lock().unwrap();
-                *zero_mutex = true;
-                self.zero_cvar.notify_one();
+            if *mutex > self.n {
+                return;
             }
+            print_number("even", *mutex / 2);
+            *mutex += 1;
+            self.cvar.notify_all();
         }
     }
 
     pub fn odd(&self) {
         loop {
-            let odd_num;
-            {
-                let mut num_mutex = self.odd_mutex.lock().unwrap();
-                loop {
-                    if *num_mutex == -1 {
-                        return;
-                    }
-                    if *num_mutex != 0 {
-                        break;
-                    }
-                    num_mutex = self.odd_cvar.wait(num_mutex).unwrap();
-                }
-
-                odd_num = *num_mutex;
-                *num_mutex = 0;
+            let mut mutex = self.mutex.lock().unwrap();
+            while *mutex <= self.n && (*mutex % 2 != 0 || *mutex % 4 == 0) {
+                mutex = self.cvar.wait(mutex).unwrap();
             }
-
-            print_number("odd", odd_num);
-
-            {
-                let mut zero_mutex = self.zero_mutex.lock().unwrap();
-                *zero_mutex = true;
-                self.zero_cvar.notify_one();
+            if *mutex > self.n {
+                return;
             }
+            print_number("odd", *mutex / 2);
+            *mutex += 1;
+            self.cvar.notify_all();
         }
     }
 }