最大子数组和

 1 /***************************************
 2 FileName MaxSumSubArray.cpp
 3 Author : godfrey
 4 CreatedTime : 2016/5/4
 5 ****************************************/
 6 #include <iostream>
 7 #include <cstring>
 8 #include <vector>
 9 #include <algorithm>
10 #include <stdio.h>
11 #include <stdlib.h>
12 
13 using namespace std;
14 
15 int MaxSumSubArray(int* A,int size,int& from,int& to){
16     if( !A || size <= 0){//错误检测
17         from = -1;
18         to = -1;
19         return 0;
20     }
21     from = to = 0;
22     int sum = A[0];//当前子串的和
23     int result = sum;//当前子串的最优解
24     int FromUpdate;
25     for(int i=1;i<size;i++){
26         if(sum > 0){
27             sum += A[i];
28         }
29         else{
30             sum = A[i];
31             FromUpdate = i;//在sum<0时，更新子数组起点
32         }
33 
34         if(result < sum){//当前最优解更新的时候，起点终点都更新
35             result = sum;
36             from = FromUpdate;
37             to = i;
38         }
39     }
40     return result;
41 }
42 int main()
43 {
44     int a[] = {1,-2,3,10,-4,7,2,-5};
45     int start,end;
46     int result = MaxSumSubArray(a,sizeof(a)/sizeof(int),start,end);
47     cout<<"the MaxSumSubArray: ";
48     cout<<result<<endl;
49     cout<<"start: "<<start<<" end: "<<end<<endl;
50     cout<<"The subArray is : "<<endl;
51     for(int i = start;i<=end;i++){
52         cout<<a[i]<<" ";
53     }
54     cout<<endl;
55     return 0;
56 }