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

方法一：動態規劃。

public class Solution {
    public boolean canJump(int[] nums) {
        boolean[] reach = new boolean[nums.length];
        reach[0] = true;
        int far = 0;
        for(int i=0; i<nums.length-1; i++) {
            if (!reach[i]) continue;
            for(int j=far+1; j<= Math.min(nums.length-1, i+nums[i]); j++) {
                reach[j] = true;
                if (j==nums.length-1) return true;
            }
            far = Math.min(nums.length-1, i+nums[i]);
        }
        return reach[nums.length-1];
    }
}
 

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