Add solutions to day 6

2016/day-06/src/main.rs

@@ -0,0 +1,60 @@
+use std::env;
+use std::io::prelude::*;
+use std::io::BufReader;
+use std::fs::File;
+use std::collections::HashMap;
+
+fn most_frequent(counts: &HashMap<char, i32>) -> char
+{
+    let (mut c, mut freq) = (' ', 0);
+    for (cc, cfreq) in counts {
+        if *cfreq > freq {
+            freq = *cfreq;
+            c = *cc;
+        }
+    }
+    return c;
+}
+
+fn least_frequent(counts: &HashMap<char, i32>) -> char
+{
+    let (mut c, mut freq) = (' ', i32::max_value());
+    for (cc, cfreq) in counts {
+        if *cfreq < freq {
+            freq = *cfreq;
+            c = *cc;
+        }
+    }
+    return c;
+}
+
+fn main() {
+    println!("Hello, world!");
+
+    let args: Vec<String> = env::args().collect();
+    let f = File::open(&args[1]).expect("Could not open file");
+    let reader = BufReader::new(f);
+
+    let mut counts: Vec<HashMap<char, i32>> = Vec::new();
+
+    for line in reader.lines() {
+        for (i, c) in line.unwrap().trim().chars().enumerate() {
+            let pos = i as usize;
+            if pos >= counts.len() {
+                counts.push(HashMap::new());
+            }
+
+            if ! counts[pos].contains_key(&c) {
+                counts[pos].insert(c, 1);
+            } else {
+                let cur = counts[pos][&c];
+                counts[pos].insert(c, cur + 1);
+            }
+        }
+    }
+
+    let decoded: String = counts.iter().map(|counts| most_frequent(counts)).collect();
+    let least_decoded: String = counts.iter().map(|counts| least_frequent(counts)).collect();
+    println!("Final (most frequent) word: {}", decoded);
+    println!("Final (least frequent) word: {}", least_decoded);
+}