返回一个整数数组中最大子数组的和（环）

 1 #include<iostream>
 2 #include<string>
 3 #include<ctime>
 5 #define N 5
 6 using namespace std;
 7 
 8 int MaxSum(int *arr, int size)
 9 {
10     int i, sum, max1, max2, dp,min;
11     dp = max1 = arr[0];
12     for (i = 1; i < size; ++i)//非环形数组;++i,先i自加1，再使用i的值
13     {
14         if (dp < 0)
15             dp = arr[i];
16         else
17             dp += arr[i];
18         if (dp > max1)
19             max1 = dp;
20     }
21     sum = min = dp = arr[0];
22     for (i = 1; i < size; ++i)//求数组最小子数组和，再用数组全部元素和减去，则结果跨过arr[n-1]到arr[0]
23     {
24         if (dp>0)
25             dp = arr[i];
26         else
27             dp += arr[i];
28         if (dp < min)
29             min = dp;
30         sum += arr[i];
31     }
32     max2 = sum - min;//数组全部元素和减去最小子数组
33     return max1>max2 ? max1 : max2;//三目运算符；如果max1>max2,将max1的值返回，否则返回max2
34 }
35 int main()
36 {
37     int arr[N];
38     srand(time(0));
39     cout << "随机数组为：" << endl;
40     for (int j = 0; j < N ; j++)
41     {
42         arr[j] = rand() % 20 - 10;
43         cout << arr[j] << " ";
44     }
45     cout << endl;
46     cout << "最大子数组的和为：" << MaxSum(arr, N) << endl;
47     return 0;
48 }