JumpGame.java

package leetcode;

/**
 * @author eko
 * @date 2018/10/23 1:30 PM
 *
 * 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.
 */
public class JumpGame {
    public static void main(String[] args) {
        int[] nums = {2, 3, 1, 1, 4};
        boolean res = new JumpGame().canJump(nums);
        System.out.println(res);
    }

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