[leetcode] Jump Game

Jump Game

Total Accepted: 32273 Total
Submissions: 118742My Submissions

Question
Solution

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

.

package com.wyt.leetcodeOJ;

/**
* @author wangyitao
* @Date 2015-01-05
* @version 1.0
* @Description
* 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 {

public static void main(String[] args) {
int[] A = {1,2,3};
System.out.println(canJump(A));
}

/**
* @param A
* @return
*
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*/
public static boolean canJump(int[] A) {
if(A == null || A.length == 0) {
return false;
}

if(A.length == 1) {
return A[0] >= 0;
}

int curMax = A[0];
int result = 0;
for (int i = 0; i < A.length;) {
int step = 0;
if (A[i] == 0 || i == A.length-1) {
break;
}
for (int j = i + 1; j <= i + (A[i] < A.length-1 ? A[i] : A.length - 1); j++) {
if (j + A[j] >= A.length) {
return true;
}
if (curMax < j + A[j]) {
curMax = j + A[j];
step = j - i;
}
}
i = step == 0 ? i+A[i] : i + step;
result = i;
}
if (result + 1 >= A.length) {
return true;
} else {
return false;
}
}
}