55. Jump Game

Author: coderbean

markdown/55. Jump Game.md

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+### [55\. Jump Game](https://leetcode.com/problems/jump-game/)
+
+Difficulty: **Medium**
+
+
+Given an array of non-negative integers, you are initially positioned at the first index of the array.
+
+Each element in the array represents your maximum jump length at that position.
+
+Determine if you are able to reach the last index.
+
+**Example 1:**
+
+```
+Input: [2,3,1,1,4]
+Output: true
+Explanation: Jump 1 step from index 0 to 1, then 3 steps to the last index.
+```
+
+**Example 2:**
+
+```
+Input: [3,2,1,0,4]
+Output: false
+Explanation: You will always arrive at index 3 no matter what. Its maximum
+             jump length is 0, which makes it impossible to reach the last index.
+```
+
+
+#### Solution
+
+Language: **Java**
+
+```java
+class Solution { // 问题可以转化为找到可以跳到的最远的距离
+    public boolean canJump(int[] nums) {
+        int max = 0;
+        for (int i = 0; i < nums.length; i++) {
+            if (i > max) return false; // 如果最远距离到达不了当前索引，没有必要继续走了
+            max = Math.max(max, nums[i] + i);
+        }
+        return true;
+    }
+}
+```
+![](http://ww1.sinaimg.cn/large/006tNc79ly1g4x1rsw78jj318w0u0gqu.jpg)

src/main/java/leetcode/_55_/Main.java

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+package leetcode._55_;
+
+import java.util.List;
+
+/**
+ * Created by zhangbo54 on 2019-03-04.
+ */
+public class Main {
+    public static void main(String[] args) {
+        Solution solution = new Solution();
+        int[] nums = {2,0,6,9,8,4,5,0,8,9,1,2,9,6,8,8,0,6,3,1,2,2,1,2,6,5,3,1,2,2,6,4,2,4,3,0,0,0,3,8,2,4,0,1,2,0,1,4,6,5,8,0,7,9,3,4,6,6,5,8,9,3,4,3,7,0,4,9,0,9,8,4,3,0,7,7,1,9,1,9,4,9,0,1,9,5,7,7,1,5,8,2,8,2,6,8,2,2,7,5,1,7,9,6};
+        boolean result = solution.canJump(nums);
+        System.out.println(result);
+    }
+}
+

src/main/java/leetcode/_55_/Solution.java

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+package leetcode._55_;
+
+class Solution { // 问题可以转化为找到可以跳到的最远的距离
+    public boolean canJump(int[] nums) {
+        int max = 0;
+        for (int i = 0; i < nums.length; i++) {
+            if (i > max) return false; // 如果最远距离到达不了当前索引，没有必要继续走了
+            max = Math.max(max, nums[i] + i);
+        }
+        return true;
+    }
+}

src/main/java/leetcode/_55_/solution.md

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+### [55\. Jump Game](https://leetcode.com/problems/jump-game/)
+
+Difficulty: **Medium**
+
+
+Given an array of non-negative integers, you are initially positioned at the first index of the array.
+
+Each element in the array represents your maximum jump length at that position.
+
+Determine if you are able to reach the last index.
+
+**Example 1:**
+
+```
+Input: [2,3,1,1,4]
+Output: true
+Explanation: Jump 1 step from index 0 to 1, then 3 steps to the last index.
+```
+
+**Example 2:**
+
+```
+Input: [3,2,1,0,4]
+Output: false
+Explanation: You will always arrive at index 3 no matter what. Its maximum
+             jump length is 0, which makes it impossible to reach the last index.
+```
+
+
+#### Solution
+
+Language: **Java**
+
+```java
+class Solution { // 问题可以转化为找到可以跳到的最远的距离
+    public boolean canJump(int[] nums) {
+        int max = 0;
+        for (int i = 0; i < nums.length; i++) {
+            if (i > max) return false; // 如果最远距离到达不了当前索引，没有必要继续走了
+            max = Math.max(max, nums[i] + i);
+        }
+        return true;
+    }
+}
+```
+![](http://ww1.sinaimg.cn/large/006tNc79ly1g4x1rsw78jj318w0u0gqu.jpg)