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
A = [2,3,1,1,4], return true.
A = [3,2,1,0,4], return false.

思路：
max[i]

  • 如果max[i−1]<i
  • 否则，更新 max[i]，max[i]=max[i−1]>(i+A[i])?max[i−1]:(i+A[i])。如果max[i]大于len-1的话如果已经可以到达终点，返回true。
  • i遍历到len-2即可
  • 其实没有必要用到max数组，只用一个max变量就可以。
class Solution {
public:
    /**
     * @param A: A list of integers
     * @return: The boolean answer
     */
    bool canJump(vector<int> A) {
        // write you code here
        int len=A.size();
        int max;
        max[0]=A[0];
        if(max[0]>=len-1){
            return true;
        }
        for(int i=1;i<len-1;i++){
            if(max[i-1]<i){
                return false;
            }else{
                max[i]=max[i-1]>(i+A[i])?max[i-1]:(i+A[i]);
            }

            if(max[i]>=len-1){
                return true;
            }
        }

    }
};