Jump Game Leetcode


#1

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.

#2

We use a greedy approach here where you pick a local optimal solution hoping to reach the global optimal solution. By adding the current steps value to the index, max will have the location of the farthest it can reach. If the current index i is greater than max then there is not a way we can reach the end, so we return false.

class Solution {
    public boolean canJump(int[] nums) {
        int max = 0;
        for(int i=0;i<nums.length;i++){
            if(i>max) return false;
            max = Math.max(nums[i]+i, max);
        }
        return true;
    }
}