problem 1 2 3 in rust

1 files changed, 39 insertions, 0 deletions

diff --git a/rust/003-largest_prime_factor.rs b/rust/003-largest_prime_factor.rs
new file mode 100644
index 0000000..2b84df1
--- /dev/null
+++ b/rust/003-largest_prime_factor.rs
@@ -0,0 +1,39 @@
+/*
+* Largest prime factor
+* Problem 3
+*
+* The prime factors of 13195 are 5, 7, 13 and 29.
+* What is the largest prime factor of the number 600851475143 ?
+*/
+
+// fn is_prime(n: u64) -> bool {
+//     if n == 2 || n == 3 || n == 5 || n == 7 {
+//         return true;
+//     }
+//     if n % 2 == 0 || n % 3 == 0 {
+//         return false;
+//     }
+//
+//     for i in (6..n).step_by(6) {
+//         if n % (i - 1) == 0 || n % (i + 1) == 0 {
+//             return true;
+//         }
+//     }
+//     return false;
+// }
+
+fn main() {
+    let mut target: u64 = 600851475143;
+    let mut n: u64 = 2;
+    let mut last = 0;
+
+    while target > 1 {
+        if target % n == 0  {
+            last = n;
+            target /= n;
+            n = 2;
+        }
+        n += 1;
+    }
+    println!("{}", last);
+}