55. 跳跃游戏

class Solution {
public:
  bool canJump(vector<int>& nums) {
    int N = nums.size();
    int Rightmost = 0;
    for (int i = 0; i < N; ++i) {
      // i itself is reachable?
      if (i <= Rightmost) {
        Rightmost = std::max(Rightmost, i + nums[i]);
        // Last index is reachable?
        if (Rightmost >= nums.size() - 1)
          return true;
      }
    }
    return false;
  }
};

class Solution {
public:
  bool canJump(vector<int>& nums) {
    int MaxDistance = 0;
    for (int i = 0; i < nums.size(); ++i) {
      if (i > MaxDistance)
        return false;
      MaxDistance = max(MaxDistance, i + nums[i]);
    }
    return MaxDistance >= nums.size() - 1;
  }
};