Regenerate an id in case the previous generated id is invalide.

Now that using "cargo run" is ok! Then the user could follow the guide of
the system output to do what he/she wants to do (e.g., generate a random
problem or select a particular problem).

Author: yue2388253

src/main.rs

@@ -9,67 +9,98 @@ use std::env;
 use std::fs;
 use std::path::{Path};
 use std::io::Write;
+use std::io;
 
 /// main() helps to generate the submission template .rs
 fn main() {
-    let args: Vec<String> = env::args().collect();
-    if args.len() < 2 {
-        panic!("problem id must be provided");
-    }
-    let id_arg = &args[1];
-    let mut id :u32 = 0;
-    match id_arg.as_ref() {
-        "random" => {
-            println!("You select random mode.");
-            id = get_random_id();
-            println!("Generate random problem: {}", &id);
-        },
-        _ => {
-            id = id_arg.parse::<u32>().expect(&format!("not a number: {}", id));
+    println!("Welcome to leetcode-rust system.");
+    let mut solved_ids = get_solved_ids();
+    loop {
+        println!("Please enter a problem id, or enter \"random\" to generate a random problem.");
+        let mut is_random = false;
+        let mut id :u32 = 0;
+        let mut id_arg = String::new();
+        io::stdin().read_line(&mut id_arg)
+            .expect("Failed to read line");
+        let id_arg = id_arg.trim();
+        match id_arg {
+            "random" => {
+                println!("You select random mode.");
+                id = generate_random_id(&solved_ids);
+                is_random = true;
+                println!("Generate random problem: {}", &id);
+            },
+            _ => {
+                id = id_arg.parse::<u32>().expect(&format!("not a number: {}", id_arg));
+                if solved_ids.contains(&id) {
+                    println!("The problem you chose is invalid (the problem may have been solved \
+                              or may have no rust version).");
+                    continue;
+                }
+            }
         }
-    }
 
-    let problem = problem::get_problem(id)
-        .expect(&format!("problem #{} not found", id));
-    let code = problem.code_definition.iter()
-        .filter(|&d| { d.value == "rust" })
-        .next()
-        .expect("problem has no rust support yet");
+        let problem = problem::get_problem(id)
+            .expect(&format!("problem #{} not found", id));
+        let code = problem.code_definition.iter()
+            .filter(|&d| { d.value == "rust" })
+            .next();
+        if code.is_none() {
+            println!("Problem {} has no rust version.", &id);
+            solved_ids.push(id);
+            continue;
+        }
+        let code = code.unwrap();
 
-    let file_name = format!("n{:04}_{}", id, problem.title_slug.replace("-", "_"));
-    let file_path = Path::new("./src").join(format!("{}.rs", file_name));
-    if file_path.exists() {
-        panic!("problem already initialized");
-    }
+        let file_name = format!("n{:04}_{}", id, problem.title_slug.replace("-", "_"));
+        let file_path = Path::new("./src").join(format!("{}.rs", file_name));
+        if file_path.exists() {
+            panic!("problem already initialized");
+        }
 
-    let template = fs::read_to_string("./template.rs").unwrap();
-    let source = template
-        .replace("__PROBLEM_TITLE__", &problem.title)
-        .replace("__PROBLEM_DESC__", &build_desc(&problem.content))
-        .replace("__PROBLEM_DEFAULT_CODE__", &code.default_code)
-        .replace("__PROBLEM_ID__", &format!("{}", id))
-        .replace("__EXTRA_USE__", &parse_extra_use(&code.default_code));
+        let template = fs::read_to_string("./template.rs").unwrap();
+        let source = template
+            .replace("__PROBLEM_TITLE__", &problem.title)
+            .replace("__PROBLEM_DESC__", &build_desc(&problem.content))
+            .replace("__PROBLEM_DEFAULT_CODE__", &code.default_code)
+            .replace("__PROBLEM_ID__", &format!("{}", id))
+            .replace("__EXTRA_USE__", &parse_extra_use(&code.default_code));
 
-    let mut file = fs::OpenOptions::new()
-        .write(true)
-        .create(true)
-        .truncate(true)
-        .open(&file_path)
-        .unwrap();
+        let mut file = fs::OpenOptions::new()
+            .write(true)
+            .create(true)
+            .truncate(true)
+            .open(&file_path)
+            .unwrap();
 
-    file.write_all(source.as_bytes()).unwrap();
-    drop(file);
+        file.write_all(source.as_bytes()).unwrap();
+        drop(file);
 
-    let mut lib_file = fs::OpenOptions::new()
-        .write(true)
-        .append(true)
-        .open("./src/lib.rs")
-        .unwrap();
-    writeln!(lib_file, "mod {};", file_name);
+        let mut lib_file = fs::OpenOptions::new()
+            .write(true)
+            .append(true)
+            .open("./src/lib.rs")
+            .unwrap();
+        writeln!(lib_file, "mod {};", file_name);
+        break;
+    }
 }
 
-fn get_random_id() -> u32 {
+fn generate_random_id(except_ids : &Vec<u32>) -> u32 {
     use std::fs;
+    use rand::Rng;
+    let mut rng = rand::thread_rng();
+    loop {
+        let res :u32 = rng.gen_range(1, 1106);
+        if !except_ids.contains(&res) {
+            return res;
+        }
+        println!("Generate a random num ({}), but it is invalid (the problem may have been solved \
+                  or may have no rust version). Regenerate..", res);
+    }
+}
+
+fn get_solved_ids() -> Vec<u32> {
     let paths = fs::read_dir("./src").unwrap();
     let mut solved_ids = Vec::new();
 
@@ -83,15 +114,7 @@ fn get_random_id() -> u32 {
         let id = id.parse::<u32>().unwrap();
         solved_ids.push(id);
     }
-    use rand::Rng;
-    let mut rng = rand::thread_rng();
-    loop {
-        let res :u32 = rng.gen_range(1, 1106);
-        if !solved_ids.contains(&res) {
-            return res;
-        }
-        println!("Generate a random num ({}), but it is solved. Regenerate..", res);
-    }
+    solved_ids
 }
 
 fn parse_extra_use(code: &str) -> String {