accepted bigint

multiply_strings/src/main.rs

@@ -1,7 +1,10 @@
 pub fn multiply(num1: String, num2: String) -> String {
     //
 
-    let mut out: Vec<u32> = Vec::from_iter((0..(num1.len() + num2.len())).into_iter().map(|_| 0));
+    let mut out: Vec<u32> = (0..(num1.len() + num2.len()))
+        .into_iter()
+        .map(|_| 0)
+        .collect();
 
     let l1 = num1.len();
     let l2 = num2.len();
@@ -11,7 +14,7 @@ pub fn multiply(num1: String, num2: String) -> String {
 
     for (i2, d2) in num2.chars().rev().enumerate() {
         let mut mcarry = 0;
-        let mut tmp = Vec::from_iter((0..i2).into_iter().map(|_| 0));
+        let mut tmp: Vec<u32> = (0..i2).into_iter().map(|_| 0).collect();
         let d2 = d2.to_digit(10).unwrap();
         for d1 in num1.chars().rev() {
             let d1 = d1.to_digit(10).unwrap();
@@ -25,16 +28,17 @@ pub fn multiply(num1: String, num2: String) -> String {
         }
         merge(&mut out, &tmp);
     }
-    let out = if let Some(last) = out.last() {
+    while let Some(last) = out.last() {
         if *last == 0 {
             let len = out.len() - 1;
-            &out[0..len]
+            out = out[0..len].to_vec();
         } else {
-            &out[0..]
+            break;
+        }
+    }
+    if out.is_empty() {
+        out.push(0);
     }
-    } else {
-        &out[0..]
-    };
 
     out.iter().rev().map(|d| d.to_string()).collect()
 }
@@ -64,4 +68,6 @@ fn main() {
             .to_string(),
         "4000000000000000000000000000000000000000000000000000000000000000".to_string()
     ));
+
+    dbg!(multiply("0".to_string(), "8".to_string()));
 }