Create 03 - Bottom-Up | DP | Approach.cpp

Author: JawadSher

24 - Dynamic Programming Problems/03 - Climbing Stairs/03 - Bottom-Up | DP | Approach.cpp

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+class Solution {
+public:
+    // Function to calculate the number of ways to climb `n` stairs using dynamic programming
+    int climbStairs(int n) {
+        // Create a dp array where dp[i] will store the number of ways to reach the ith step
+        vector<int> dp(n+1, 0);
+
+        // Base case: There's one way to reach the 0th step (by staying at the start)
+        dp[0] = 1;
+
+        // Base case: If n >= 1, there's one way to reach the 1st step (by taking a single step)
+        if(n >= 1) dp[1] = 1;
+
+        // Iterate from the 2nd step to the nth step
+        for(int i = 2; i <= n; i++) {
+            // The number of ways to reach step i is the sum of:
+            //   - the number of ways to reach step i-1 (taking 1 step)
+            //   - the number of ways to reach step i-2 (taking 2 steps)
+            dp[i] = dp[i-1] + dp[i-2];
+        }
+
+        // Return the number of ways to reach the nth step
+        return dp[n];
+    }
+};