进阶工程代码3.21

?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77

#include<iostream> #include<vector>   using namespace std;   int MaxSubArraySum_1(const vector<int> &arr){     int n=arr.size();     if(n==0)         return 0;     int sum=arr[0];     int max=arr[0];     for(int i=1;i<n;i++){         if(sum>=0)             sum+=arr[i];         else             sum=arr[i];         if(sum>max)             max=sum;     }     return max; }   int MaxSubArraySum_2(const vector<int> &arr){     int n=arr.size();     if(n==0)         return 0;     vector<int> maxSub(n);     maxSub[0]=arr[0];     int max=arr[0];     for(int i=1;i<n;i++){         maxSub[i]=(maxSub[i-1]>0)?(maxSub[i-1]+arr[i]):arr[i];         if(max<maxSub[i])             max=maxSub[i];     }     return max; }   int MaxSubMatrixSum(const vector<vector<int> > &arr){     int m=arr.size();     int n=arr[0].size();     vector<vector<int> > total(m,vector<int>(n,0));       for(int i=0;i<n;i++)         total[0][i]=arr[0][i];       for(int i=1;i<m;i++){         for(int j=0;j<n;j++){             total[i][j]=total[i-1][j]+arr[i][j];         }     }       int max=-1000;     vector<int> result(n);     for(int i=0;i<m;i++){         for(int j=i;j<m;j++){             for(int f=0;f<n;f++){                 if(i==0)                     result[f]=total[j][f];                 else                     result[f]=total[j][f]-total[i-1][f];             }                      int maximal=MaxSubArraySum_2(result);             if(maximal>max)                 max=maximal;           }     }       return max; }    int main(){     vector<vector<int> > mat={{0,-2,-7,0},{9,2,-6,2},{-4,1,-4,1},{-1,8,0,-2}};     cout<< MaxSubMatrixSum(mat);     return 0; }