Add exercise 372, 378

e_372/Cargo.toml

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+[package]
+name = "e_372"
+version = "0.1.0"
+authors = ["Emelie Graven <emelie@graven.dev>"]
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

e_372/src/main.rs

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+/*!
+ # Description
+Given a string containing only the characters `x` and `y`, find whether there are the same number of `x`s and `y`s.
+
+    balanced("xxxyyy") => true
+    balanced("yyyxxx") => true
+    balanced("xxxyyyy") => false
+    balanced("yyxyxxyxxyyyyxxxyxyx") => true
+    balanced("xyxxxxyyyxyxxyxxyy") => false
+    balanced("") => true
+    balanced("x") => false
+
+## Optional bonus
+
+Given a string containing only lowercase letters, find whether every letter that appears in the string appears the same number of times. Don't forget to handle the empty string (`""`) correctly!
+
+    balanced_bonus("xxxyyyzzz") => true
+    balanced_bonus("abccbaabccba") => true
+    balanced_bonus("xxxyyyzzzz") => false
+    balanced_bonus("abcdefghijklmnopqrstuvwxyz") => true
+    balanced_bonus("pqq") => false
+    balanced_bonus("fdedfdeffeddefeeeefddf") => false
+    balanced_bonus("www") => true
+    balanced_bonus("x") => true
+    balanced_bonus("") => true
+
+Note that `balanced_bonus` behaves differently than `balanced` for a few inputs, e.g. `"x"`.
+ */
+
+use std::collections::HashMap;
+
+fn main() {
+    println!("{}", balanced(String::from("jbsssssh")));
+}
+
+fn balanced(input: String) -> bool {
+    let count: HashMap<char, i32> = input.chars().fold(HashMap::new(), |mut map, ch| {
+        map.entry(ch).and_modify(|n| *n += 1).or_insert(1);
+        map
+    });
+    println!("{:?}", count);
+    let mut values = count.values();
+    if let Some(first) = values.next() {
+        values.all(|x| x == first)
+    } else {
+        true
+    }
+}