# Easy 标签
题目 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? 假设你正在爬楼梯。需要 n 阶你才能到达楼顶。 每次你可以爬 1 或 2 个台阶。你有多少种不同的方法可以爬到楼顶呢？ 注意：给定 n 是一个正整数。 示例 1： 输入： 2 输出： 2 解释： 有两种方法可以爬到楼顶。 1. 1 阶 + 1 阶 2. 2 阶 示例 2： 输入： 3 输出： 3 解释： 有三种方法可以爬到楼顶。 1. 1 阶 + 1 阶 + 1 阶 2. 1 阶 + 2 阶 3. 2 阶 + 1 阶 解法 要爬到第 n 阶，可以在 n-1 阶爬 1 步上去，或 n-2 阶爬 2 步上去。 所以可以得出 f(n)=f(n-1)+f(n-2) 即斐波那契数列 一 动态规划 思路 使用数组每个值 代码 二 使用斐波那契数列公式....

[70] Climbing Stairs

LeetCode
题目 Implementint sqrt(int x). Compute and return the square root of_x_, where x is guaranteed to be a non-negative integer. Since the return type is an integer, the decimal digits are truncated and only the integer part of the result is returned. Example 1: Input: 4 Output: 2 Example 2: Input: 8 Output: 2 Explanation: The square root of 8 is 2.82842..., and since   the decimal part is truncated, 2 is returned. 解法 一：使用Math.sqrt()方法 代码 class Solution { public int mySqrt(i....

[69] Sqrt(x)

LeetCode
题目 Given anon-emptyarray of digits representing a non-negative integer, plus one to the integer. The digits are stored such that the most significant digit is at the head of the list, and each element in the array contain a single digit. You may assume the integer does not contain any leading zero, except the number 0 itself. Example 1: Input: [1,2,3] Output: [1,2,4] Explanation: The array represents the integer 123. Example 2: Input: [4,3,2,1] Output: [4,3,2,2] Explanation: The array repr....

[66] Plus One

LeetCode
题目 The count-and-say sequence is the sequence of integers with the first five terms as following: 1. 1 2. 11 3. 21 4. 1211 5. 111221 1is read off as"one 1"or11. 11is read off as"two 1s"or21. 21is read off as"one 2, thenone 1"or1211. Given an integer_n_ where 1 ≤_n_≤ 30, generate the_n_thterm of the count-and-say sequence. Note: Each term of the sequence of integers will be represented as a string. Example 1: Input: 1 Output: "1" Example 2: Input: 4 Output: "1211" 解法 一 思路 遍历时使用变量记录当前数字及次数....

[38] Count and Say

LeetCode
题目 Given a sorted array and a target value, return the index if the target is found. If not, return the index where it would be if it were inserted in order. You may assume no duplicates in the array. Example 1: Input: [1,3,5,6], 5 Output: 2 Example 2: Input: [1,3,5,6], 2 Output: 1 Example 3: Input: [1,3,5,6], 7 Output: 4 Example 4: Input: [1,3,5,6], 0 Output: 0 解法 一：暴力 思路 for循环即可 代码 二：二分查找 思路 使用二分查找 代码

[35] Search Insert Position

LeetCode