[leetcode]45. Jump Game II(Java)

https://leetcode.com/problems/jump-game-ii/#/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.

Your goal is to reach the last index in the minimum number of jumps.

For example:
Given array A = [2,3,1,1,4]

The minimum number of jumps to reach the last index is 2. (Jump 1 step from index 0 to 1, then 3 steps to the last index.)

Note:
You can assume that you can always reach the last index.

Java Code:

package go.jacob.day625;

public class Demo1 {

	/*
	 * Runtime: 9 ms. Your runtime beats 93.99 % of java submissions.
	 * 参考自leetcode网友：@adam20
	 * 
	 * The main idea is based on greedy. Let's say the range of the current jump
	 * is [curBegin, curEnd], curFarthest is the farthest point that all points
	 * in [curBegin, curEnd] can reach. Once the current point reaches curEnd,
	 * then trigger another jump, and set the new curEnd with curFarthest, then
	 * keep the above steps, as the following
	 */
	public int jump(int[] A) {
		int jumps = 0, curEnd = 0, curFarthest = 0;
		for (int i = 0; i < A.length - 1; i++) {
			curFarthest = Math.max(curFarthest, i + A[i]);
			if (i == curEnd) {
				jumps++;
				curEnd = curFarthest;
			}
		}
		return jumps;
	}

}