[编程题]求最大值

题目来源：牛客网

[编程题] 最大和
在一个N*N的数组中寻找所有横，竖，左上到右下，右上到左下，四种方向的直线连续D个数字的和里面最大的值
输入描述:
每个测试输入包含1个测试用例，第一行包括两个整数 N 和 D :
3 <= N <= 100
1 <= D <= N
接下来有N行，每行N个数字d:
0 <= d <= 100

输出描述:
输出一个整数，表示找到的和的最大值

输入例子:
4 2
87 98 79 61
10 27 95 70
20 64 73 29
71 65 15 0

输出例子:
193

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注意不要漏掉边界情况

#include <iostream>#include <vector>using namespace std;int main(void){    int row, num;    cin >> row >> num;    if (num > row)    {        return 0;    }    else    {        int sum = row*row;        int **input = (int**)malloc(row*sizeof(int*));        for (int i = 0; i < row; i++)        {            input[i] = new int[row];            for (int j = 0; j < row; j++)            {                int cur;                cin >> cur;                input[i][j] = cur;            }        }        int maxsum = -1;        int rownum, colnum, cnt, pos, cursum;        //所有水平方向的和        for (rownum = 0; rownum < row; rownum++)        {            for (colnum = 0; colnum <= row - num; colnum++)            {                cnt = num;                pos = colnum;                cursum = 0;                for (; cnt>0; cnt--)                {                    cursum += input[rownum][pos];                    pos++;                }                if (cursum > maxsum)                    maxsum = cursum;            }        }        //所有垂直方向的和        for (colnum = 0; colnum < row; colnum++)//每一列        {            for (rownum = 0; rownum <= row - num; rownum++)            {                cnt = num;                pos = rownum;                cursum = 0;                for (; cnt>0; cnt--)                {                    cursum += input[pos][colnum];                    pos++;                }                if (cursum > maxsum)                    maxsum = cursum;            }        }        //所有主对角线的和        for (rownum = 0; rownum <= row - num; rownum++)        {            for (colnum = 0; colnum < row - num; colnum++)            {                cnt = num;                pos = 0;                cursum = 0;                for (; cnt>0; cnt--)                {                    cursum += input[rownum + pos][colnum + pos];                    pos++;                }                if (cursum > maxsum)                    maxsum = cursum;            }        }        //所有次对角线的和        for (rownum = 0; rownum <= row - num; rownum++)        {            for (colnum = num - 1; colnum < row; colnum++)            {                cnt = num;                pos = 0;                cursum = 0;                for (; cnt>0; cnt--)                {                    cursum += input[rownum + pos][colnum - pos];                    pos++;                }                if (cursum > maxsum)                    maxsum = cursum;            }        }        cout << maxsum;        return 0;    }    return 0;}