杭电-oj triangle(数学找规律)

问题描述
A triangle field is numbered with successive integers in the way shown on the picture below.

The traveller needs to go from the cell with number M to the cell with number N. The traveller is able to enter the cell through cell edges only, he can not travel from cell to cell through vertices. The number of edges the traveller passes makes the length of the traveller’s route.

Write the program to determine the length of the shortest route connecting cells with numbers N and M.

Input
Input contains two integer numbers M and N in the range from 1 to 1000000000 separated with space(s).

Output
Output should contain the length of the shortest route.

Sample Input
6 12

Sample Output
3

大致题意及思路
这是一个数学题，需要找出计算规律。
要想算出m到n的距离，需要从一个地方按行走、按左下方向走和按右下方向走，把这三个距离都加起来就得到了距离。

就是上图三个角度，他们之间存在线的和，比如3到13。横线的3和13之间存在两个水平线，计算方法为13那行对应末尾16开根号，为4，3对应那行末尾数字4开根号为2。两者之差为2。同理 /left也是末尾开根号，而\right，从第二行开始，是开头的开根号再加一。

代码

#include 
#include 
void find(int n, int &l, int &r, int &level)
{
    int i;
    level = 1;
    for (i = 1; ; i += 2)
    {
        if (n - i <= 0)
        {
            l = (n + 1) / 2;      /*左边层次*/
            r = (i - n) / 2 + 1;  /*右边层次*/
            break;
        }
        level++;  /*层次*/
        n -= i;
    }
}
 
int main()
{
    int m, n;
    int ml, mr, nl, nr, mlevel, nlevel;
    while(scanf("%d%d", &m, &n) != EOF)
    {
        find(m, ml, mr, mlevel);
        find(n, nl, nr, nlevel);
        printf("%d\n", abs(ml - nl) + abs(mr - nr) + abs(mlevel - nlevel));
    }
    return 0;
}

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