Given an integer array nums, find the contiguous subarray within an array (containing at least one number) which has the largest product.
Example 1:
Input: [2,3,-2,4]
Output: 6
Explanation: [2,3] has the largest product 6.
Example 2:
Input: [-2,0,-1]
Output: 0
Explanation: The result cannot be 2, because [-2,-1] is not a subarray.题目链接：https://leetcode.com/problems/maximum-product-subarray/
class Solution {
public:
int maxProduct(vector<int>& nums) {
int n=nums.size();
int m=nums[0];
vector<vector<int>> dp(n,vector<int>(2,0));
dp[0][0]=m;
dp[0][1]=m;//dp[i][0]最大值，dp[i][0]最小值
for(int i=1;i<n;i++)
{
dp[i][0]=max(nums[i],max(nums[i]*dp[i-1][0],nums[i]*dp[i-1][1]));
dp[i][1]=min(nums[i],min(nums[i]*dp[i-1][0],nums[i]*dp[i-1][1]));
if(dp[i][0]>m)
m=dp[i][0];
}
return m;
}
};其实那个dp二维数组，没有必要
class Solution {
public:
int maxProduct(vector<int>& nums) {
int n=nums.size();
int m=nums[0];
int big=m;
int small=m;
for(int i=1;i<n;i++)
{
int tmpbig=big;
big=max(nums[i],max(nums[i]*big,nums[i]*small));
small=min(nums[i],min(nums[i]*tmpbig,nums[i]*small));//一定是上一次的big，也就是tmpbig
if(big>m)
m=big;
}
return m;
}
};