optimized day 4

src/day4/1.rs

@@ -10,9 +10,9 @@ fn solution(ip: &'static str) -> usize {
     let mut input: Vec<u8> = ip.bytes().collect();
     let l = input.len();
 
-    loop {
+    let mut t = Vec::with_capacity(32);
-        let mut t = vec![];
 
+    loop {
         let mut n = num;
         while n != 0 {
             let d = n % 10;
@@ -21,29 +21,29 @@ fn solution(ip: &'static str) -> usize {
             n /= 10;
         }
 
-        input.extend(t.into_iter().rev());
+        input.extend(t.iter().rev());
 
-        let c = md5_compute(input.clone());
+        let ans = md5_compute(&mut input);
 
-        if c[0..2] == [0, 0] && c[2] & 0b11110000 == 0 {
+        if ans.to_be() < 4096 {
             return num;
         }
 
         input.resize(l, 0);
 
+        t.clear();
+
         num += 1;
     }
 }
-
+// s specifies the per-round shift amounts
-fn md5_compute(mut ip: Vec<u8>) -> [u8; 16] {
+const S: [u32; 64] = [
-    // s specifies the per-round shift amounts
-    const S: [u32; 64] = [
     7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22, // 0..15
     5, 9, 14, 20, 5, 9, 14, 20, 5, 9, 14, 20, 5, 9, 14, 20, // 16..31
     4, 11, 16, 23, 4, 11, 16, 23, 4, 11, 16, 23, 4, 11, 16, 23, // 32..47
     6, 10, 15, 21, 6, 10, 15, 21, 6, 10, 15, 21, 6, 10, 15, 21, // 48..63
-    ];
+];
-    const K: [u32; 64] = [
+const K: [u32; 64] = [
     0xd76aa478, 0xe8c7b756, 0x242070db, 0xc1bdceee, // 0..3
     0xf57c0faf, 0x4787c62a, 0xa8304613, 0xfd469501, // 4..7
     0x698098d8, 0x8b44f7af, 0xffff5bb1, 0x895cd7be, // 8..11
@@ -60,8 +60,9 @@ fn md5_compute(mut ip: Vec<u8>) -> [u8; 16] {
     0x655b59c3, 0x8f0ccc92, 0xffeff47d, 0x85845dd1, // 52..55
     0x6fa87e4f, 0xfe2ce6e0, 0xa3014314, 0x4e0811a1, // 56..59
     0xf7537e82, 0xbd3af235, 0x2ad7d2bb, 0xeb86d391, // 60..63
-    ];
+];
 
+fn md5_compute(ip: &mut Vec<u8>) -> u32 {
     let l = ip.len();
 
     // Padding
@@ -76,14 +77,14 @@ fn md5_compute(mut ip: Vec<u8>) -> [u8; 16] {
 
     ip.extend((l * 8).to_le_bytes());
 
-    let input: Vec<u32> = ip
-        .chunks(4)
-        .map(|chunk| u32::from_le_bytes([chunk[0], chunk[1], chunk[2], chunk[3]]))
-        .collect();
-
     let mut state: [u32; 4] = [0x67452301, 0xefcdab89, 0x98badcfe, 0x10325476];
 
-    for chunk in input.chunks(16) {
+    for chunk in ip.chunks(64).map(|chunk| {
+        chunk
+            .chunks(4)
+            .map(|c| u32::from_le_bytes([c[0], c[1], c[2], c[3]]))
+            .collect::<Vec<u32>>()
+    }) {
         let mut lstate = state;
 
         for i in 0..64 {
@@ -122,13 +123,7 @@ fn md5_compute(mut ip: Vec<u8>) -> [u8; 16] {
         state[3] += lstate[3];
     }
 
-    let mut hash = [0; 16];
+    state[0]
-
-    for (i, c) in state.map(|c| c.to_le_bytes()).flatten().iter().enumerate() {
-        hash[i] = *c;
-    }
-
-    hash
 }
 
 fn main() {

src/day4/2.rs

@@ -10,9 +10,9 @@ fn solution(ip: &'static str) -> usize {
     let mut input: Vec<u8> = ip.bytes().collect();
     let l = input.len();
 
-    loop {
+    let mut t = Vec::with_capacity(32);
-        let mut t = vec![];
 
+    loop {
         let mut n = num;
         while n != 0 {
             let d = n % 10;
@@ -21,29 +21,29 @@ fn solution(ip: &'static str) -> usize {
             n /= 10;
         }
 
-        input.extend(t.into_iter().rev());
+        input.extend(t.iter().rev());
 
-        let c = md5_compute(input.clone());
+        let ans = md5_compute(&mut input);
 
-        if c[0..3] == [0, 0, 0] {
+        if ans.to_be() < 256 {
             return num;
         }
 
         input.resize(l, 0);
 
+        t.clear();
+
         num += 1;
     }
 }
-
+// s specifies the per-round shift amounts
-fn md5_compute(mut ip: Vec<u8>) -> [u8; 16] {
+const S: [u32; 64] = [
-    // s specifies the per-round shift amounts
-    const S: [u32; 64] = [
     7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22, // 0..15
     5, 9, 14, 20, 5, 9, 14, 20, 5, 9, 14, 20, 5, 9, 14, 20, // 16..31
     4, 11, 16, 23, 4, 11, 16, 23, 4, 11, 16, 23, 4, 11, 16, 23, // 32..47
     6, 10, 15, 21, 6, 10, 15, 21, 6, 10, 15, 21, 6, 10, 15, 21, // 48..63
-    ];
+];
-    const K: [u32; 64] = [
+const K: [u32; 64] = [
     0xd76aa478, 0xe8c7b756, 0x242070db, 0xc1bdceee, // 0..3
     0xf57c0faf, 0x4787c62a, 0xa8304613, 0xfd469501, // 4..7
     0x698098d8, 0x8b44f7af, 0xffff5bb1, 0x895cd7be, // 8..11
@@ -60,8 +60,9 @@ fn md5_compute(mut ip: Vec<u8>) -> [u8; 16] {
     0x655b59c3, 0x8f0ccc92, 0xffeff47d, 0x85845dd1, // 52..55
     0x6fa87e4f, 0xfe2ce6e0, 0xa3014314, 0x4e0811a1, // 56..59
     0xf7537e82, 0xbd3af235, 0x2ad7d2bb, 0xeb86d391, // 60..63
-    ];
+];
 
+fn md5_compute(ip: &mut Vec<u8>) -> u32 {
     let l = ip.len();
 
     // Padding
@@ -76,14 +77,14 @@ fn md5_compute(mut ip: Vec<u8>) -> [u8; 16] {
 
     ip.extend((l * 8).to_le_bytes());
 
-    let input: Vec<u32> = ip
-        .chunks(4)
-        .map(|chunk| u32::from_le_bytes([chunk[0], chunk[1], chunk[2], chunk[3]]))
-        .collect();
-
     let mut state: [u32; 4] = [0x67452301, 0xefcdab89, 0x98badcfe, 0x10325476];
 
-    for chunk in input.chunks(16) {
+    for chunk in ip.chunks(64).map(|chunk| {
+        chunk
+            .chunks(4)
+            .map(|c| u32::from_le_bytes([c[0], c[1], c[2], c[3]]))
+            .collect::<Vec<u32>>()
+    }) {
         let mut lstate = state;
 
         for i in 0..64 {
@@ -122,13 +123,7 @@ fn md5_compute(mut ip: Vec<u8>) -> [u8; 16] {
         state[3] += lstate[3];
     }
 
-    let mut hash = [0; 16];
+    state[0]
-
-    for (i, c) in state.map(|c| c.to_le_bytes()).flatten().iter().enumerate() {
-        hash[i] = *c;
-    }
-
-    hash
 }
 
 fn main() {