1 files changed, 76 insertions, 0 deletions
diff --git a/03/src/part-2.rs b/03/src/part-2.rs
new file mode 100644
index 0000000..e3cda54
--- /dev/null
+++ b/03/src/part-2.rs
@@ -0,0 +1,76 @@
+use std::io::{BufRead};
+
+const GROUP_SIZE: usize = 3;
+
+fn main() {    
+    let stdin = std::io::stdin();
+    let mut handle = stdin.lock();
+    
+    let all_ones: u64 = {
+        let mut ret: u64 = 0;
+        for i in 0..64 {
+            ret |= 1 << i;
+        }
+        ret
+    };
+
+    let mut result: usize = 0;
+    let mut buf: Vec<u8> = Vec::new();
+    let mut done: bool = false;
+    
+    loop {
+        let mut set: u64 = all_ones;
+
+        for i in 0..GROUP_SIZE {
+            buf.clear();
+            let num_bytes = handle.read_until(b'\n', &mut buf).expect("IO error");
+            if num_bytes == 0 {
+                if i == 0 {
+                    done = true;
+                    break;
+                }
+                else { panic!("Malformed input"); }
+            }
+
+            let stripped_buf: & [u8] = {
+                if buf[buf.len() - 1] == b'\n' {
+                    & buf[0..buf.len()-1]
+                }
+                else {
+                    & buf
+                }
+            };
+
+            assert!(!stripped_buf.is_empty());
+
+            let mut seen: u64 = 0;
+            
+            for &c in stripped_buf {
+                assert!((c >= 65 && c <= 90) || (c >= 97 && c <= 122));
+                if c <= 90 {
+                    seen |= 1 << (c - b'A');
+                }
+                else {
+                    seen |= 1 << (c - b'a' + 26);
+                }
+            }
+            set &= seen;
+        }
+
+        if done { break; }
+
+        assert_eq!(set.count_ones(), 1);
+
+        for i in 0..26 {
+            if set & (1 << i) != 0 {
+                result += 26 + i + 1;
+                break;
+            }
+            if set & (1 << (26 + i)) != 0 {
+                result += i + 1;
+                break;
+            }
+        }
+    }
+    println!("{}", result);
+}