Merge pull request #1000 from Horiol/master

#755 Catalan numbers in Rust

Algorithms/DynamicProgramming/catalan_horiol.rs

@@ -0,0 +1,28 @@
+use std::io;
+
+fn main() {
+    println!("Enter number value: ");
+    let mut input = String::new();
+    io::stdin().read_line(&mut input).ok().expect("failed to read line");
+    let val: u64 = input.trim().parse().expect("Please type a number");
+    println!("Catalan number is: {}", catalan(val));
+}
+
+fn catalan(n: u64) -> u64 {
+    if n == 0 || n == 1 {
+        return 1;
+    }    
+
+    let mut catalan_list = Vec::new();
+    catalan_list.push(1);
+    catalan_list.push(1);
+
+    for index in 2..(n+1) {
+        catalan_list.push(0);
+        for other_index in 0..index {
+            catalan_list[index as usize] = catalan_list[index as usize] 
+            + catalan_list[other_index  as usize] * catalan_list[(index - other_index - 1)  as usize];
+        }
+    }
+    return catalan_list[n as usize];
+}