/**
* Source : https://oj.leetcode.com/problems/jump-game/
*
* Created by lverpeng on 2017/7/17.
*
* 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.
*/
public class JumpGame {
/**
* max记录目前能到的最远位置,循环数组,每次max和当前i能到的最远位置作比较,如果比max大,说明能到比原来到更远的位置,更新max
* 如果max已经大于等于数组长度,则说明能到数组末尾,返回true
* 如果当前已经大于max说明当前位置已经到不了,返回false
*
* 如果上面没有返回,说明不能到数组末尾
*
* @param arr
* @return
*/
public boolean canJump (int[] arr) {
if (arr.length <= 0) {
return false;
}
int length = arr.length;
// 记录最远能到的位置
int max = 0;
for (int i = 0; i < max && i < length - 1; i++) {
if (i + arr[i] > max) {
max = i +arr[i];
}
if (max >= length - 1) {
return true;
}
}
return false;
}
public static void main(String[] args) {
JumpGame jumpGame = new JumpGame();
int[] arr = new int[]{2,3,1,1,4};
int[] arr1 = new int[]{3,2,1,0,4};
int[] arr2 = new int[]{3,2,1,0,4,1};
System.out.println("true---->" + jumpGame.canJump(arr));
System.out.println("false--->" + jumpGame.canJump(arr1));
System.out.println("false--->" + jumpGame.canJump(arr2));
}
}