Basic diff

src/main.rs

@@ -1,3 +1,50 @@
-fn main() {
+use std::cmp::min;
-    println!("Hello, world!");
+use std::io;
+use crate::matrix::Matrix;
+
+mod matrix;
+
+const ADD_VAL: i32 = 1;
+const MATCH_VAL: i32 = 0;
+
+fn main() -> io::Result<()> {
+    let str_a = "String A";
+    let str_b = "String B";
+
+    let mut diff_mat = Matrix::new(str_a.len(), str_b.len(), 0i32);
+
+    for col in 1..diff_mat.col_count {
+        let previous = diff_mat.get(0, col - 1).unwrap();
+        diff_mat.set(previous + ADD_VAL, 0, col).expect("Failed to initialize diff matrix");
+    }
+
+    for row in 1..diff_mat.row_count {
+        let previous = diff_mat.get(row - 1, 0).unwrap();
+        diff_mat.set(previous - ADD_VAL, row, 0).expect("Failed to initialize diff matrix");
+    }
+
+    for row in 1..diff_mat.row_count {
+        for col in 1..diff_mat.col_count {
+            let char_a = str_a.chars().nth(row).unwrap();
+            let char_b = str_b.chars().nth(col).unwrap();
+
+            let add_from = diff_mat.get(row, col - 1).unwrap();
+            let sub_from = diff_mat.get(row - 1, col).unwrap();
+            let substitute_from = diff_mat.get(row - 1, col - 1).unwrap();
+
+            let add = add_from + ADD_VAL;
+            let sub = sub_from - ADD_VAL;
+            let substitute = substitute_from + if char_a == char_b {
+                MATCH_VAL
+            } else {
+                1
+            };
+
+            let val = min(add, min(sub, substitute));
+            diff_mat.set(val, row, col).unwrap();
+        }
+    }
+
+    diff_mat.print();
+    Ok(())
 }

src/matrix.rs

@@ -1,9 +1,10 @@
+use std::fmt::{Debug, Display, Formatter};
 use std::ops;
 
 #[derive(Debug)]
 pub struct Matrix<T> {
-    row_count: usize,
+    pub row_count: usize,
-    col_count: usize,
+    pub col_count: usize,
     default_val: T,
     rows: Vec<Vec<T>>,
 }
@@ -52,6 +53,20 @@ impl<T> Matrix<T> where
     }
 }
 
+impl<T> Matrix<T> where
+    T: Display, T: Copy {
+    pub fn print(&self) {
+        for row in 0..self.row_count {
+            for col in 0..self.col_count {
+                let val = self.rows[row][col];
+                print!(" {val} ");
+            }
+
+            print!("\n");
+        }
+    }
+}
+
 impl<T> ops::Add<Matrix<T>> for Matrix<T> where
     T: ops::Add<Output=T>, T: Copy {
     type Output = Result<Matrix<T>, MatrixError>;