【LeetCode】 45. Jump Game II

45. Jump Game II

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.

思路：

DP(自底向上)，数组dp[]表示能够到达该位置最小的steps，有一点类似最短上升子序列。

#include<iostream>
#include<vector>
using namespace std;
int minJump(vector<int>& nums)
{
	int* dp = new int[(nums.size())];
	for(int i=1;i<(nums.size());i++) dp[i]=INT_MAX;
	dp[0]=0;
	for(int i=0;i<(nums.size());i++){
		for(int j=i+1;j<=i+nums[i]&&j<(nums.size());j++){
			if(dp[i]+1<dp[j]) dp[j]=dp[i]+1;
		}
	} 
	int ans = dp[(nums.size()-1)];
	delete[] dp;
	return ans;
 } 
 int main(void)
 {
 	vector<int> input;
 	int size;
 	while(cin>>size){
 		int num;
 		for(int i=0;i<size;i++){
 			cin>>num;
 			input.push_back(num);
		 }
		 cout<<minJump(input)<<endl;
	 }
	 return 0;
 }