From de9fb772c707aaf3c6cbc3cc24b2a42aeced8920 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Gr=C3=A9gory=20Burri?= <gregory.burri@matisa.ch>
Date: Mon, 9 Dec 2019 14:54:35 +0100
Subject: [PATCH] Day 05

---
 src/day05.rs | 111 ++++++++++++++++++++++++++++++++++++++++++++++-----
 src/main.rs  |  11 +++++
 2 files changed, 112 insertions(+), 10 deletions(-)

diff --git a/src/day05.rs b/src/day05.rs
index 1ff5739..61f6203 100644
--- a/src/day05.rs
+++ b/src/day05.rs
@@ -1,33 +1,124 @@
-fn read_code(code: i32) -> (i32, Vec<bool>) {
+// 'true' -> immediate mode, 'false' -> position mode.
+fn read_op_and_modes(mut code: i32) -> (i32, [bool; 3]) {
+    let mut modes: [bool; 3] = [ false, false, false ];
 
+    if code >= 10_000 {
+        modes[2] = true;
+        code -= 10_000;
+    }
+
+    if code >= 1_000 {
+        modes[1] = true;
+        code -= 1_000;
+    }
+
+    if code >= 100 {
+        modes[0] = true;
+        code -= 100;
+    }
+
+    (code, modes)
 }
 
-fn execute_op_code(code: &mut [i32], input: &[i32]) -> Vec<i32> {
+pub fn execute_op_code(code: &mut [i32], input: &[i32]) -> Vec<i32> {
     let mut cursor = 0;
+    let mut input_cursor = 0;
     let mut output = Vec::<i32>::new();
+
+    fn read(position: usize, code: &[i32], mode: bool) -> i32 {
+        if mode { code[position] } else { code[code[position] as usize] }
+    };
+
+    fn jump_if(cond: bool, cursor: usize, code: &[i32], modes: [bool; 3]) -> usize {
+        let value = read(cursor + 1, &code, modes[0]);
+        if cond == (value != 0) {
+            read(cursor + 2, &code, modes[1]) as usize
+        } else {
+            cursor + 3
+        }
+    };
+
     loop {
-        match code[cursor] {
-            1 => code[code[cursor + 3] as usize] = code[code[cursor + 1] as usize] + code[code[cursor + 2] as usize],
-            2 => code[code[cursor + 3] as usize] = code[code[cursor + 1] as usize] * code[code[cursor + 2] as usize],
-            99 => return code[0],
+        let (op, modes) = read_op_and_modes(code[cursor]);
+
+        match op {
+            // Sum.
+            1 => {
+                code[code[cursor + 3] as usize] = read(cursor + 1, &code, modes[0]) + read(cursor + 2, &code, modes[1]);
+                cursor += 4;
+            },
+
+            // Multiply.
+            2 => {
+                code[code[cursor + 3] as usize] = read(cursor + 1, &code, modes[0]) * read(cursor + 2, &code, modes[1]);
+                cursor += 4;
+            },
+
+            // Input.
+            3 => {
+                code[code[cursor + 1] as usize] = input[input_cursor];
+                input_cursor += 1;
+                cursor += 2;
+            }
+
+            // Output.
+            4 => {
+                output.push(read(cursor + 1, &code, modes[0]));
+                cursor += 2;
+            }
+
+            // Jump-if-true.
+            5 => cursor = jump_if(true, cursor, &code, modes),
+
+            // Jump-if-false.
+            6 => cursor = jump_if(false, cursor, &code, modes),
+
+            // Less than.
+            7 => {
+                code[code[cursor + 3] as usize] =
+                    if read(cursor + 1, &code, modes[0]) < read(cursor + 2, &code, modes[1]) { 1 } else { 0 };
+                cursor += 4;
+            },
+
+            // Equals.
+            8 => {
+                code[code[cursor + 3] as usize] =
+                    if read(cursor + 1, &code, modes[0]) == read(cursor + 2, &code, modes[1]) { 1 } else { 0 };
+                cursor += 4;
+            },
+
+            99 => break,
             _ => panic!("Unkown code: {}", code[cursor])
         }
-        cursor += 4;
     }
+    output
 }
 
-
-
-
 #[cfg(test)]
 mod tests {
     use super::*;
 
     #[test]
     fn part1() {
+        let mut c = [1002, 4, 3, 4, 33];
+        let _ = execute_op_code(&mut c, &Vec::new());
+        assert_eq!(c[4], 99);
     }
 
     #[test]
     fn part2() {
+        let c = [3,21,1008,21,8,20,1005,20,22,107,8,21,20,1006,20,31,1106,0,36,98,0,0,1002,21,125,20,4,20,1105,1,46,104,999,1105,1,46,1101,1000,1,20,4,20,1105,1,46,98,99];
+
+        let mut c1 = c;
+        let r1 = execute_op_code(&mut c1, &[7]);
+        assert_eq!(r1[0], 999);
+
+        let mut c2 = c;
+        let r2 = execute_op_code(&mut c2, &[8]);
+        assert_eq!(r2[0], 1000);
+
+        let mut c3 = c;
+        let r3 = execute_op_code(&mut c3, &[9]);
+        assert_eq!(r3[0], 1001);
     }
 }
\ No newline at end of file
diff --git a/src/main.rs b/src/main.rs
index d0dbfc3..eaccb71 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -29,6 +29,15 @@ fn day03() -> String {
     )
 }
 
+fn day04() -> String {
+    format!("")
+}
+
+fn day05() -> String {
+    let code = common::read_list_of_numbers("data/day05.input", ",");
+    format!("part1: {:?}, part2: {:?}", day05::execute_op_code(&mut Vec::from(&code[..]), &[1]), day05::execute_op_code(&mut Vec::from(&code[..]), &[5]))
+}
+
 fn day06() -> String {
     let file_content = fs::read_to_string("data/day06.input").unwrap();
     let lines: Vec<&str> = file_content.lines().collect();
@@ -58,6 +67,8 @@ fn main() {
         day01,
         day02,
         day03,
+        day04,
+        day05,
         day06
     );
 
-- 
2.45.2