Second huge commit

2016/day05/src/main.rs

@@ -0,0 +1,79 @@
+extern crate crypto;
+
+use crypto::md5::Md5;
+use crypto::digest::Digest;
+
+//This was mostly stolen from a github gist that I found while looking for a Rust MD5 library
+fn part_1() {
+    let mut hasher = Md5::new();
+
+    let key = "reyedfim".as_bytes();
+    let mut answer: Vec<u8> = vec![];
+
+    let mut count = 8;
+    for i in 0..std::u64::MAX {
+        hasher.input(key);
+        hasher.input(i.to_string().as_bytes());
+
+        let mut output = [0; 16]; //represents MD5 string
+        hasher.result(&mut output);
+
+        //check the first two and a half bytes of the output
+        let first_five = output[0] as i32 + output[1] as i32 + (output[2] >> 4) as i32;
+        if first_five == 0 {
+            let output_str: String = output.iter().map(|&c| format!("{:x}{:x}", c >> 4, c)).collect();
+            println!("hashed {} to get {}", i, output_str);
+            answer.push(output[2]);
+            match count > 1 {
+                true => count -= 1,
+                false => break,
+            }
+        }
+        hasher.reset();
+    }
+    let answer_str: String = answer.iter().map(|&c| format!("{:x}", c)).collect();
+    println!("Part 1: Answer is {}", answer_str);
+}
+
+fn part_2() {
+    let mut hasher = Md5::new();
+
+    let key = "reyedfim".as_bytes();
+    let mut answer = [0; 8];
+    let mut answer_mask = [true; 8];
+
+    for i in 0..std::u64::MAX {
+        hasher.input(key);
+        hasher.input(i.to_string().as_bytes());
+
+        let mut output = [0; 16]; //represents MD5 string
+        hasher.result(&mut output);
+
+        //check the first two and a half bytes of the output
+        let first_five = output[0] as i32 + output[1] as i32 + (output[2] >> 4) as i32;
+        if first_five == 0 {
+            let output_str: String = output.iter().map(|&c| format!("{:x}{:x}", c >> 4, c)).collect();
+            println!("hashed {} to get {}", i, output_str);
+            //answer.push(output[2]);
+            let idx = output[2] as usize;
+            let val = output[3] >> 4;
+            if idx < 8 && answer_mask[idx] {
+                answer[idx] = val;
+                answer_mask[idx] = false; //we filled this slot
+                println!("Values are {} and {}", idx, val);
+                match answer_mask.iter().fold(false, |f, &i| f || i) {
+                    true => {}, //keep going
+                    false => break, //we're all done here
+                }
+            }
+        }
+        hasher.reset();
+    }
+    let answer_str: String = answer.iter().map(|&c| format!("{:x}", c)).collect();
+    println!("Part 1: Answer is {}", answer_str);
+}
+
+fn main() {
+    //part_1();
+    part_2();
+}