HOJ Delta-wave

题目链接

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

这是参考链接
这是参考链接
这是参考链接

总结：主要是找规律，重点在找两个数的坐标，可以巧妙的运用坐标系。
注意取绝对值函数，abs与fabs
int abs(int i); // 处理int类型的取绝对值
double fabs(double i); //处理double类型的取绝对值
float fabsf(float i); /处理float类型的取绝对值

代码：

#include <iostream>#include <cmath>using namespace std;int main(){    int a,b;    int aLayer,bLayer;    int aX,aY,bX,bY;    int distance;    while(cin >> a >> b){        aLayer = ceil(sqrt(a));        bLayer = ceil(sqrt(b));        if(aLayer == bLayer)            distance = b - a;        else{            aX = (aLayer * aLayer - a) / 2;            aY = aLayer - (aLayer * aLayer - a + 1) / 2 - 1;            bX = (bLayer * bLayer - b) / 2;            bY = bLayer - (bLayer * bLayer - b + 1) / 2 - 1;            distance = abs(aX - bX) + abs(aY - bY) + abs(aLayer - bLayer);        }        cout << distance << endl;    }}