Jump Game

[leetcode]Jump Game

链接：https://leetcode.com/problems/jump-game/description/

Question

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

// 从头开始，每次i+nums[i]都可以找到可以到达的最远地方。用maxLocation记录最远可以到达的地方。
class Solution {
public:
  bool canJump(vector<int>& nums) {
    int maxLocation = 0;
    for (int i = 0; i < nums.size(); i++) {
      // 从i到不了
      if (i > maxLocation) return false;
      if (i+nums[i] > maxLocation) maxLocation = i+nums[i];
      if (maxLocation > nums.size()) return true;
    }
    return true;
  }
};

思路：这里的关键点在于你只需要知道每一格自己可到最远是哪里就可以了，同时你要保证当前格是可以到达的。