day 8 solution

2018/day8/Cargo.lock

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+[[package]]
+name = "day8"
+version = "0.1.0"
+

2018/day8/Cargo.toml

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+[package]
+name = "day8"
+version = "0.1.0"
+authors = ["Andrew Coleman <penguincoder@gmail.com>"]
+edition = "2018"
+
+[dependencies]

2018/day8/src/main.rs

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+use std::fs::File;
+use std::io::{BufRead, BufReader};
+use std::iter::Iterator;
+
+fn calc_metadata_sum(ints: &mut Vec<i32>) -> i32 {
+    let subnode_count = ints.remove(0);
+    let metadata_count = ints.remove(0);
+    let mut sum = 0;
+    for _i in 0..subnode_count {
+        sum += calc_metadata_sum(ints);
+    }
+    for _i in 0..metadata_count {
+        sum += ints.remove(0);
+    }
+    sum
+}
+
+fn calc_node_sum(ints: &mut Vec<i32>) -> i32 {
+    let subnode_count = ints.remove(0);
+    let metadata_count = ints.remove(0);
+
+    let mut node_sums: Vec<i32> = Vec::with_capacity(subnode_count as usize);
+    for _i in 0..subnode_count {
+        node_sums.push(calc_node_sum(ints));
+    }
+
+    let mut metadatas: Vec<i32> = Vec::with_capacity(metadata_count as usize);
+    for _i in 0..metadata_count {
+        metadatas.push(ints.remove(0));
+    }
+
+    if subnode_count == 0 {
+        metadatas.iter().sum()
+    } else {
+        let mut sum = 0;
+        for m in metadatas.iter() {
+            let index = (m - 1) as usize;
+            if m <= &subnode_count {
+                sum += node_sums[index];
+            }
+        }
+        sum
+    }
+}
+
+fn main() {
+    let mut line = String::new();
+    BufReader::new(File::open("input").unwrap()).read_line(&mut line).unwrap();
+    let len_withoutcrlf = line.trim_right().len();
+    line.truncate(len_withoutcrlf);
+    let ints: Vec<i32> = line.as_str().split(" ").map(|i| i.parse::<i32>().unwrap()).collect();
+    let sum = calc_metadata_sum(&mut ints.clone());
+    println!("part 1 sum is {}", sum);
+    let sum2 = calc_node_sum(&mut ints.clone());
+    println!("part 2 sum is {}", sum2);
+}