Day 1, part 1

.gitignore

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+/target

Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "aoc2021"
+version = "0.1.0"

Cargo.toml

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+[package]
+name = "aoc2021"
+version = "0.1.0"
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

src/main.rs

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+use std::io;
+use std::io::prelude::*;
+use std::env;
+use std::fs::File;
+
+
+fn main() -> io::Result<()> {
+    let args: Vec<String> = env::args().collect();
+    let f = File::open(&args[1])?;
+    let buf = io::BufReader::new(f);
+    let mut last = -1;
+    let mut count_incr = 0;
+    for line in buf.lines() {
+        if let Ok(l) = line {
+            if let Ok(value) = i32::from_str_radix(&l, 10) {
+                if last > 0 && value > last {
+                    count_incr += 1;
+                }
+                last = value;
+            }
+        }
+    }
+    println!("number of increases: {}", count_incr);
+    Ok(())
+}