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.

For example:
A = [2,3,1,1,4], return true.

A = [3,2,1,0,4], return false.

 1 class Solution {
 2 public:
 3     bool canJump(int A[], int n) {
 4         int reach = 0;
 5         for (int i = 0; i <= reach && i < n; ++i) {
 6             reach = max(reach, A[i] + i);
 7             if (reach >= n - 1) {
 8                 return true;
 9             }
10         }
11         return reach >= n - 1;
12     }
13 };

View Code

用一个reach变量保存可以达到的最远位置，从前向后扫描不断地扩大reach的范围，若reach可以达到目标位置则返回true.