20240804 Finished

src/problem/mod.rs

@@ -194,3 +194,4 @@ mod p172_factorial_trailing_zeroes;
 mod p69_sqrtx;
 mod p50_powx_n;
 mod p149_max_points_on_a_line;
+mod p70_climbing_stairs;

src/problem/p70_climbing_stairs.rs

@@ -0,0 +1,42 @@
+/**
+ * [70] Climbing Stairs
+ */
+pub struct Solution {}
+
+
+// submission codes start here
+
+impl Solution {
+    pub fn climb_stairs(n: i32) -> i32 {
+        if n == 1 {
+            return 1;
+        } else if n == 2 {
+            return 2;
+        }
+        
+        let mut last_last = 1;
+        let mut last = 2;
+        
+        for i in 3..=n {
+            let now = last + last_last;
+            last_last = last;
+            last = now;
+        }
+        
+        last
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_70() {
+        assert_eq!(2, Solution::climb_stairs(2));
+        assert_eq!(3, Solution::climb_stairs(3));
+        assert_eq!(5, Solution::climb_stairs(4));
+    }
+}