poj 2243 a星搜索

a星算法我不介紹了，參考這個鏈接http://my.oschina.net/u/211101/blog/126259

直接上這個題目的代碼：

#include <iostream>
#include <cstring>
#include <cstdio>
#include <queue>
#include <cmath>

using namespace std;
int dir_x[] = {-2, -1, 1, 2, 2, 1, -1, -2};
int dir_y[] = {1, 2, 2, 1, -1, -2, -2, -1};

const int row = 8;
const int col = 8;
struct node
{
	int x;
	int y;
	int step;

	int g, h, f;
	node(){}
	node(int x, int y, int step, int g, int h, int f):x(x), y(y), step(step), g(g), h(h), f(f){}
	bool operator < (const node &a) const
	{
		return f > a.f;
	}
	
};
bool vis[row + 2][col + 2];


node start, end;

bool judgeSide(const node &tmp)   //判斷tmp點是否在棋盤上面
{
	return tmp.x >= 1 && tmp.x <= 8 && tmp.y >= 1 && tmp.y <= 8;
}
int heuristic(const int &x, const int &y)     //啓發值
{
	return (abs(x - end.x) + abs(y - end.y)) * 10;
}
priority_queue<node> pq;
int aStare()
{
	node top, tmp;

	while(!pq.empty())
	{
		top = pq.top();
		pq.pop();
		vis[top.x][top.y] = true;
		if(top.x == end.x && top.y == end.y)
			return top.step;
		for(int i = 0; i < 8; i++)
		{
			
			tmp.x = top.x + dir_x[i], tmp.y = top.y + dir_y[i], tmp.step = top.step + 1, tmp.g = top.g + 23, tmp.h = heuristic(tmp.x, tmp.y), tmp.f = tmp.g + tmp.h;
			if(judgeSide(tmp) && vis[tmp.x][tmp.y] == false)
			{
				pq.push(tmp);
			}
			
		}
	}

}
int main()
{
	char c1, c2;
	while(cin >> c1 >> start.y >> c2 >> end.y)
	{
		memset(vis, false, sizeof(vis));
		while(!pq.empty())
			pq.pop();
		start.x = c1 - 'a' + 1;
		start.step = 0;
		start.g = 0, start.h = heuristic(start.x, start.y), start.f = start.g + start.h;
		end.x = c2 - 'a' + 1;
		
		pq.push(start);
		int res = aStare();
		cout << "To get from " << c1 << start.y << " to " << c2 << end.y << " takes " << res << " knight moves." << endl;
	}
}