Maximum Product Subarray

標籤：

Find the contiguous subarray within an array (containing at least one number) which has the largest product.

For example, given the array [2,3,-2,4],
the contiguous subarray [2,3] has the largest product = 6.

 

依舊是DP演算法，由於負數乘以負數也可以變成一個很大的數，因此要維護2個局部最優變數，局部最大和局部最小，代碼如下：

public class Solution {        public int Min(int a,int b) {        return a<b?a:b;    }        public int Max(int a,int b) {        return a>b?a:b;    }        public int maxProduct(int[] A) {        int size = A.length;        int local_max = A[0];//局部最大        int local_min = A[0];//局部最小        int global = A[0];//全域最大        for(int i=1;i<size;i++) {            int tmp = local_max;            local_max = Max(Max(local_max*A[i],A[i]),local_min*A[i]);            local_min = Min(Min(tmp*A[i],A[i]),local_min*A[i]);            global = Max(global,local_max);        }        return global;    }}

 

Maximum Product Subarray