Rust: 1D_dynamic_array, 3 solutions

Author: tomijaga

rust/03_sliding_window/121_best_time_to_buy.rs

@@ -1,4 +1,5 @@
-use super::std::cmp;
+use std::cmp;
+
 impl Solution {
     pub fn max_profit(prices: Vec<i32>) -> i32 {
         let mut l = 0;
@@ -7,11 +8,11 @@ impl Solution {
         while r < prices.len() {
             if prices[l] < prices[r] {
                 let profit = prices[r] - prices[l];
-                max_profit = cmp::max(profit, max_profit)
+                max_profit = cmp::max(profit, max_profit);
             } else {
-                l = r
+                l = r;
             }
-            r += 1
+            r += 1;
         }
         max_profit
     }

rust/13_1D_dynamic_programming/198_house_robber.rs

@@ -0,0 +1,18 @@
+// time complexity: O(n)
+// space complexity: O(1)
+
+impl Solution {
+    pub fn rob(mut nums: Vec<i32>) -> i32 {
+        if nums.len() == 1{
+            return nums[0];
+        }
+        
+        nums[1] = nums[0].max(nums[1]);
+        
+        for i in 2..nums.len(){
+            nums[i] = nums[i-1].max(nums[i - 2] + nums[i]);
+        }
+        
+        *nums.last().unwrap()
+    }
+}

rust/13_1D_dynamic_programming/70_climbing_stairs.rs

@@ -0,0 +1,18 @@
+
+impl Solution {
+    pub fn climb_stairs(n: i32) -> i32 {
+        if n == 1{
+            return 1;
+        }
+        
+        let (mut one, mut two) = (1, 2);
+
+        for i in 2..n{
+            let tmp = two;
+            two = two + one;
+            one = tmp;
+        }
+        
+        two
+    }
+}

rust/13_1D_dynamic_programming/746_min_cost_climbing_stairs.rs

@@ -0,0 +1,14 @@
+//  time compexity : O(n)
+// space compexity : O(1)
+
+impl Solution {
+    pub fn min_cost_climbing_stairs(mut cost: Vec<i32>) -> i32 {
+        for i in 2..cost.len(){
+            cost[i] += cost[i- 1].min(cost[i-2]);
+        }
+        
+        let len = cost.len();
+        
+        cost[len - 1].min(cost[len - 2])
+    }
+}