LeetCode-jump-game-ii

题目描述

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 is2. (Jump1step from index 0 to 1, then3steps to the last index.)

Leetcode链接

# 这里使用广度优先搜索，
# 对于每一个选取区间，比如index=0时，nums[index]=2,
# 则区间为1-2，遍历i=1-2;找到index+nums[i]的最大值，就能够(覆盖)其中的任何值

# 所以这里只需要选取max(nextMax,i+nums[i])就行，具体思路看代码想一想就通了

class Solution(object):
    def jump(self, nums):
        """
        :type nums: List[int]
        :rtype: int
        """
        n = len(nums)
        if n < 2:
            return 0

        # 分别表示当前可选择最大节点下标、下一个节点下标、游标、计数次数
        currentMax = 0
        nextMax = 0
        i = 0
        number = 0
        while currentMax-i>=0:
            number = number+1
            while i<=currentMax:
                nextMax = max(nextMax,i+nums[i])
                if nextMax >= n-1:
                    return number
            currentMax = nextMax

        return 0;