# [LeetCode] 45. Jump Game II 跳跃游戏 II

2021年09月15日 阅读数：2

Given an array of non-negative integers, you are initially positioned at the first index of the array.html

Each element in the array represents your maximum jump length at that position.java

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

Example:python

```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:c++

You can assume that you can always reach the last index.post

Java:blog

```class Solution {
public int jump(int[] A) {
int sc = 0;
int e = 0;
int max = 0;
for(int i=0; i<A.length-1; i++) {
max = Math.max(max, i+A[i]);
if( i == e ) {
sc++;
e = max;
}
}
return sc;
}
}　　```

Python: BFS游戏

```class Solution:
# @param {integer[]} nums
# @return {integer}
def jump(self, nums):
n, start, end, step = len(nums), 0, 0, 0
while end < n - 1:
step += 1
maxend = end + 1
for i in range(start, end + 1):
if i + nums[i] >= n - 1:
return step
maxend = max(maxend, i + nums[i])
start, end = end + 1, maxend
return step　　```

C++: BFS

```class Solution {
public:
int jump(int A[], int n) {
if(n<2)return 0;
int level=0,currentMax=0,i=0,nextMax=0;

while(currentMax-i+1>0){		//nodes count of current level>0
level++;
for(;i<=currentMax;i++){	//traverse current level , and update the max reach of next level
nextMax=max(nextMax,A[i]+i);
if(nextMax>=n-1)return level;   // if last element is in level+1,  then the min jump=level
}
currentMax=nextMax;
}
return 0;
}
};
```

[LeetCode] 55. Jump Game 跳跃游戏