Interview 150

Min Cost Climbing Stairs

Problem
LC 746
File
interview150_LC746MinCostClimbingStairs.java
Path
pkg5leetcode/interview150/interview150_LC746MinCostClimbingStairs.java
Package
pkg5leetcode.interview150
Command
java pkg5leetcode/interview150/interview150_LC746MinCostClimbingStairs.java
Approach
DP min cost to reach each step from prior two.
Complexity
Time O(n), Space O(1)

LeetCode solutions

There is no in-browser runner. This is the file from the curriculum, unchanged.

pkg5leetcode/interview150/interview150_LC746MinCostClimbingStairs.java
1package pkg5leetcode.interview150;2 3/*4 * Min Cost Climbing Stairs | LC 7465 * APPROACH: DP min cost to reach each step from prior two.6 * COMPLEXITY: Time O(n), Space O(1)7 */8public class interview150_LC746MinCostClimbingStairs {9    static int minCostClimbingStairs(int[] cost) {10        int a = 0, b = 0;11        for (int i = 2; i <= cost.length; i++) {12            int c = Math.min(a + cost[i - 2], b + cost[i - 1]);13            a = b;14            b = c;15        }16        return b;17    }18 19    public static void main(String[] args) {20        check(minCostClimbingStairs(new int[]{10, 15, 20}) == 15, "case1");21        check(minCostClimbingStairs(new int[]{1, 100, 1, 1, 1, 100, 1, 1, 100, 1}) == 6, "case2");22        System.out.println("all tests passed");23    }24 25    static void check(boolean cond, String name) {26        if (!cond) throw new AssertionError("FAILED: " + name);27        System.out.println("  PASS " + name);28    }29}