Data commit

Task/Longest-common-subsequence/Rust/longest-common-subsequence.rust

@@ -0,0 +1,56 @@
+use std::cmp;
+
+fn lcs(string1: String, string2: String) -> (usize, String){
+    let total_rows = string1.len() + 1;
+    let total_columns = string2.len() + 1;
+    // rust doesn't allow accessing string by index
+    let string1_chars = string1.as_bytes();
+    let string2_chars = string2.as_bytes();
+
+    let mut table = vec![vec![0; total_columns]; total_rows];
+
+    for row in 1..total_rows{
+        for col in 1..total_columns {
+            if string1_chars[row - 1] == string2_chars[col - 1]{
+                table[row][col] = table[row - 1][col - 1] + 1;
+            } else {
+                table[row][col] = cmp::max(table[row][col-1], table[row-1][col]);
+            }
+        }
+    }
+
+    let mut common_seq = Vec::new();
+    let mut x = total_rows - 1;
+    let mut y = total_columns - 1;
+
+    while x != 0 && y != 0 {
+        // Check element above is equal
+        if table[x][y] == table[x - 1][y] {
+            x = x - 1;
+        }
+        // check element to the left is equal
+        else if table[x][y] == table[x][y - 1] {
+            y = y - 1;
+        }
+        else {
+            // check the two element at the respective x,y position is same
+            assert_eq!(string1_chars[x-1], string2_chars[y-1]);
+            let char = string1_chars[x - 1];
+            common_seq.push(char);
+            x = x - 1;
+            y = y - 1;
+        }
+    }
+    common_seq.reverse();
+    (table[total_rows - 1][total_columns - 1], String::from_utf8(common_seq).unwrap())
+}
+
+fn main() {
+    let res = lcs("abcdaf".to_string(), "acbcf".to_string());
+    assert_eq!((4 as usize, "abcf".to_string()), res);
+    let res = lcs("thisisatest".to_string(), "testing123testing".to_string());
+    assert_eq!((7 as usize, "tsitest".to_string()), res);
+    // LCS for input Sequences “AGGTAB” and “GXTXAYB” is “GTAB” of length 4.
+    let res = lcs("AGGTAB".to_string(), "GXTXAYB".to_string());
+    assert_eq!((4 as usize, "GTAB".to_string()), res);
+}