HD 1003 Max Sum 的递归解法

#include <STDIO.H>
typedef struct SU_tag{
    SU_tag(){}
    SU_tag(int a,int b,int c):max_sum(a),left(b),right(c){}
    int max_sum;
    int left;
    int right;
}SU;

SU find_max_crossing_subarray(int *a,int low,int mid,int high)
{
    int left,left_max=a[mid],right,right_max=a[mid+1],i,sum;
    sum=0;
    for(i=mid;i>=low;i--){
        sum+=a[i];
        if(sum>=left_max){
            left_max=sum;
            left = i;
        }
    }
    sum=0;
    for(i=mid+1;i<=high;i++){
        sum+=a[i];
        if(sum>=right_max){
            right_max = sum;
            right = i;
        }
    }
    return SU(left_max+right_max,left,right);
}

SU find_max_subarray(int *a,int low,int high)
{
    SU left,right,cross;
    if(low == high){
        return SU(a[low],low,high);
    }else{
        int mid = (low+high)/2;
        left = find_max_subarray(a,low,mid);
        right = find_max_subarray(a,mid+1,high);
        cross = find_max_crossing_subarray(a,low,mid,high);
    }
    if(left.max_sum>=right.max_sum && left.max_sum>=cross.max_sum)
        return left;
    else if(cross.max_sum>=left.max_sum && cross.max_sum>=right.max_sum)
        return cross;
    else
        return right;
}

int main()
{
    int t,n,i;
    scanf("%d",&t);
    i = 1;
    while(i<=t){
        scanf("%d",&n);
        int m=0,*a=new int[n];
        for(;m<n;m++)
            scanf("%d",&a[m]);
        SU r = find_max_subarray(a,0,n-1);
        printf("Case %d:\n",i);
        printf("%d %d %d\n",r.max_sum,r.left+1,r.right+1);
        if(i!=t)
            printf("\n");
        delete a;
        i++;
    }
    return 0;
}