求最大子串和的3种方法

   一直都没来得及完成关于算法课上的实验任务，今天终于算是有时间把这个给写了。

#include<cstdio>#include<cstdlib>#include<cstring>#include<cmath>#include<iostream>using namespace std;//蛮力法int maxSum(int a[],int n){    int maxsum=0;    int sum=0;    for(int i=0;i<n;i++){         sum=a[i];       for(int j=i+1;j<n;j++){           if(sum>=maxsum){              maxsum=sum;           }           sum+=a[j];     }    }     return maxsum;}//分治法int maxSum1(int a[],int left,int right){    int sum=0;    if(left==right){        if(a[left]>0)           sum=a[left];        else           sum=0;    }    else{         int center=(left+right)/2;         int leftsum=maxSum1(a,left,center);         int rightsum=maxSum1(a,center+1,right);         int s1=0,lefts=0;         for(int i=center;i>left;i--){                lefts+=a[i];                if(lefts>s1) s1=lefts;         }         int s2=0,rights=0;         for(int i=center+1;i<=right;i++){                rights+=a[i];                if(rights>s2) s2=rights;         }         sum=s1+s2;         if(sum<leftsum) sum=leftsum;         if(sum<rightsum) sum=rightsum;    }    return  sum;}//动态规划int Dpsum(int a[],int n){    int sum=0;    int *b=(int *)malloc(n*sizeof(int));    b[0]=a[0];    for(int i=1;i<n;i++){        if(b[i-1]>0){            b[i]=b[i-1]+a[i];        }        else            b[i]=a[i];    }    for(int j=0;j<n;j++){        if(b[j]>sum)  sum=b[j];    }    delete []b;    return sum;}int main(){     int a[10000];     int n;     printf("要输入的序列的个数:");        scanf("%d",&n);     printf("要输入的一系列数为:");     for(int i=0;i<n;i++){        scanf("%d",&a[i]);     }     int ans1=maxSum(a,n);     int ans2=maxSum1(a,0,n);     int ans3=Dpsum(a,n);     printf("最大的子串和为:%d\n",ans1);     printf("最大的子串和为:%d\n",ans2);     printf("最大的子串和为:%d\n",ans3);     return 0;}