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.

注意这里的每个位上的数是可以跳跃的最大长度，应该使用贪心策略，看了别人的实现，代码如下，以后好好思考下：

 class Solution {

 public:

     bool canJump(vector<int>& nums) {

         int sz = nums.size();

         if(!sz) return false;

         int left = nums[];

         for(int i = ; i < sz; ++i)

             if(left > ){

                 left--;

                 left = max(left, nums[i]);

             }else return false;

         return true;

     }

 };