add: 跳跃游戏 II

README.md

@@ -235,6 +235,11 @@ LeetCode 与 LintCode 解题记录。此为个人练习仓库，代码中对重
   - LeetCode 面试题42. 连续子数组的最大和 https://leetcode-cn.com/problems/lian-xu-zi-shu-zu-de-zui-da-he-lcof/
   - LintCode 41. 最大子数组 https://www.lintcode.com/problem/maximum-subarray/description
 
+- [跳跃游戏II](src/array/jump-game-ii.js)
+
+  - LeetCode 45. 跳跃游戏 II https://leetcode-cn.com/problems/jump-game-ii/
+  - LintCode 117. 跳跃游戏 II https://www.lintcode.com/problem/jump-game-ii/description
+
 ## 栈
 
 - [最大矩阵](src/stack/maximal-rectangle.js)

src/array/jump-game-ii.js

@@ -0,0 +1,20 @@
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+export const jump = function (nums) {
+  let step = 0 // 跳跃步数
+  let maxPosition = 0 // 最大位置
+  let lastJumpStepMax = 0 // 最后一次跳跃最大能跳的步数
+
+  for (let n = 0, len = nums.length; n < len - 1; n++) {
+    maxPosition = Math.max(maxPosition, nums[n] + n)
+    if (lastJumpStepMax === n) { // 从当前位置开始，到当前能跳的位置这个区间，谁最大，就选谁，并跳一次
+      lastJumpStepMax = maxPosition
+      step++
+    }
+    if (lastJumpStepMax > len) return step
+  }
+
+  return step
+}

test/array/jump-game-ii.test.js

@@ -0,0 +1,5 @@
+import { jump } from '../../src/array/jump-game-ii'
+
+test('跳跃游戏II', () => {
+  expect(jump([2, 3, 1, 1, 4])).toBe(2)
+})