45. Jump Game II (JAVA)

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.

Example:

Input: [2,3,1,1,4]
Output: 2
Explanation: 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.

贪心算法，每次step都是选择最远的那个。

class Solution {
    public int jump(int[] nums) {
        if(nums.length == 1) return 0; //no need steps
        
        int start = 1; //start index of current step
        int end = nums[0]; //end index of current step
        int step = 1; //minimum steps
        int maxStep = 0; //furthest index of current step
        while(end < nums.length-1){
            for(int i = start; i <= end; i++){
                maxStep = Math.max(maxStep, nums[i]+i);
            }
            start = end+1;
            end = maxStep;
            step++;
        }
        return step;
    }
}