杭电OJ——1030 Delta-wave

Delta-wave

Problem Description

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

 

Source

Ural Collegiate Programming Contest 1998

 

Recommend

lcy

 

       具体的算法参考这里！http://blog.sina.com.cn/s/blog_790ba68b01016sxc.html

代码如下：

#include <stdio.h>#include <math.h>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;}