day 7: part 2: rust

2015/days/07/part2/Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "part2"
+version = "0.1.0"

2015/days/07/part2/Cargo.toml

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+[package]
+name = "part2"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]

2015/days/07/part2/src/main.rs

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+use core::panic;
+use std::io;
+use std::collections::BTreeMap;
+
+type Formula = String;
+type Variable = String;
+
+fn emulate(circuit: &Vec<(Formula, Variable)>, variables: &mut BTreeMap<Variable, u16>, target: &Variable) {
+    while !variables.contains_key(target) {
+        let mut update = true;
+        for command in circuit {
+            let variable = &command.1;
+            let formula = &command.0;
+            if variables.contains_key(variable) {
+                continue;
+            }
+            let number = formula.parse::<u16>();
+            if number.is_ok() {
+                variables.insert(variable.clone(), number.unwrap());
+                update = true;
+            } else if formula.starts_with("NOT") {
+                let mut parts = formula.split(" ");
+                parts.next();
+                let negated = parts.next().unwrap().to_string();
+                if variables.contains_key(&negated) {
+                    let value = !(*variables.get(&negated).unwrap());
+                    variables.insert(variable.clone(), value);
+                    update = true;
+                }
+            } else if !formula.contains(" "){
+                if variables.contains_key(formula) {
+                    let value = *variables.get(formula).unwrap();
+                    variables.insert(variable.clone(),value);
+                    update = true;
+                }
+            } else {
+                let mut parts = formula.split(" ");
+                let operand_a = parts.next().unwrap();
+                let operator = parts.next().unwrap();
+                let operand_b = parts.next().unwrap();
+                let operand_a_u16_result = operand_a.parse::<u16>();
+                let operand_b_u16_result = operand_b.parse::<u16>();
+                if (!operand_a_u16_result.is_ok() && !variables.contains_key(operand_a)) 
+                    || (!operand_b_u16_result.is_ok() && !variables.contains_key(operand_b)) {
+                    continue;
+                }
+                let operand_a_u16: u16;
+                let operand_b_u16: u16;
+                if operand_a_u16_result.is_ok() {
+                    operand_a_u16 = operand_a_u16_result.unwrap();
+                } else {
+                    operand_a_u16 = *variables.get(operand_a).unwrap();
+                }
+                if operand_b_u16_result.is_ok() {
+                    operand_b_u16 = operand_b_u16_result.unwrap();
+                } else {
+                    operand_b_u16 = *variables.get(operand_b).unwrap();
+                }
+                let value = match operator {
+                    "AND" => operand_a_u16 & operand_b_u16,
+                    "OR" => operand_a_u16 | operand_b_u16,
+                    "LSHIFT" => operand_a_u16 << operand_b_u16,
+                    "RSHIFT" => operand_a_u16 >> operand_b_u16,
+                    &_ => 0,
+                };
+                variables.insert(variable.clone(), value);
+                update = true;
+            }
+
+        }
+
+        if !update {
+            panic!("I cannot progress in the emulation, target cannot be reached");
+        } 
+    }
+}
+
+fn main() -> io::Result<()> {
+    let mut variables: BTreeMap<Variable, u16> = BTreeMap::new();
+    let wire_a: Variable = "a".to_string();
+    let mut circuit: Vec<(Formula, Variable)> = Vec::new();
+    for line in io::stdin().lines() {
+        let line = line.unwrap();
+        let mut parts = line.split(" -> ");
+        let formula: Formula = parts.next().unwrap().to_string();
+        let variable: Variable = parts.next().unwrap().to_string();
+        circuit.push((formula, variable));
+    }
+    emulate(&circuit, &mut variables, &wire_a);
+    let signal_b = variables.get(&wire_a).unwrap();
+    let wire_b = "b".to_string();
+    let mut new_variables: BTreeMap<Variable, u16> = BTreeMap::new();
+    new_variables.insert(wire_b.clone(), *signal_b);
+    emulate(&circuit, &mut new_variables, &wire_a);
+    println!("{}", new_variables.get(&wire_a).unwrap());
+    Ok(())
+}