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_0070_ClimbingStairs.java
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_0070_ClimbingStairs.java
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package com.diguage.algorithm.leetcode;
/**
* = 70. Climbing Stairs
*
* https://leetcode.com/problems/climbing-stairs/[Climbing Stairs - LeetCode]
*
* You are climbing a stair case. It takes n steps to reach to the top.
*
* Each time you can either climb 1 or 2 steps. In how many distinct ways can you climb to the top?
*
* *Note:* Given n will be a positive integer.
*
* .Example 1:
* [source]
* ----
* Input: 2
* Output: 2
* Explanation: There are two ways to climb to the top.
* 1. 1 step + 1 step
* 2. 2 steps
* ----
*
* .Example 2:
* [source]
* ----
* Input: 3
* Output: 3
* Explanation: There are three ways to climb to the top.
* 1. 1 step + 1 step + 1 step
* 2. 1 step + 2 steps
* 3. 2 steps + 1 step
* ----
*
*
* @author D瓜哥, https://www.diguage.com/
* @since 2020-01-23 21:29
*/
public class _0070_ClimbingStairs {
/**
* Runtime: 0 ms, faster than 100.00% of Java online submissions for Climbing Stairs.
*
* Memory Usage: 40.8 MB, less than 5.26% of Java online submissions for Climbing Stairs.
*
* Copy from: https://leetcode.com/problems/climbing-stairs/solution/[Climbing Stairs solution - LeetCode]
*/
public int climbStairs(int n) {
int[] dp = new int[n + 1];
dp[0] = 1;
dp[1] = 1;
for (int i = 2; i <= n; i++) {
dp[i] = dp[i - 1] + dp[i - 2];
}
return dp[n];
}
public static void main(String[] args) {
_0070_ClimbingStairs solution = new _0070_ClimbingStairs();
int r1 = solution.climbStairs(2);
System.out.println((r1 == 2) + " : " + r1);
int r2 = solution.climbStairs(3);
System.out.println((r2 == 3) + " : " + r2);
int r3 = solution.climbStairs(4);
System.out.println((r3 == 5) + " : " + r3);
}
}