From 10dc704069548def2922dea5c1795b1c3fce0c94 Mon Sep 17 00:00:00 2001
From: Andrew Guschin <guschin.drew@gmail.com>
Date: Fri, 17 Mar 2023 00:13:09 +0400
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---
 sem2/src/mpn.rs | 33 ++++++++++++++++++++++++++++++++-
 1 file changed, 32 insertions(+), 1 deletion(-)

(limited to 'sem2/src/mpn.rs')

diff --git a/sem2/src/mpn.rs b/sem2/src/mpn.rs
index 24880ca..b9816a3 100644
--- a/sem2/src/mpn.rs
+++ b/sem2/src/mpn.rs
@@ -1,6 +1,6 @@
 use std::cmp::max;
 use std::fmt;
-use std::ops::{Add, Sub};
+use std::ops::{Add, Mul, Sub};
 
 pub struct Number {
     radix: usize,
@@ -143,3 +143,34 @@ impl Sub for Number {
         .fix_leading_zeros();
     }
 }
+
+impl Mul for Number {
+    type Output = Self;
+
+    fn mul(self, other: Self) -> Self::Output {
+        let n = self.len();
+        let m = other.len();
+        let mut digits = vec![0; n + m];
+
+        for j in 0..m {
+            let vj = other.digits[j];
+            if vj == 0 {
+                digits[n + j] = 0;
+            } else {
+                let mut k = 0;
+                for i in 0..n {
+                    let ui = self.digits[i];
+                    let t = ui * vj + digits[i + j] + k;
+                    digits[i + j] = t % self.radix as u8;
+                    k = t / self.radix as u8;
+                }
+                digits[n + j] = k;
+            }
+        }
+        return Number {
+            radix: self.radix,
+            digits,
+        }
+        .fix_leading_zeros();
+    }
+}
-- 
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