day62|Floyd 算法精讲,A * 算法精讲 （A star算法

Floyd 算法精讲

97. 小明逛公园 (kamacoder.com)

#include 
#include 
using namespace std;

int main() {
    int n, m, p1, p2, val;
    cin >> n >> m;

    vector> grid(n + 1, vector(n + 1, 10005)); 

    for(int i = 0; i < m; i++){
        cin >> p1 >> p2 >> val;
        grid[p1][p2] = val;
        grid[p2][p1] = val;

    }
    for (int k = 1; k <= n; k++) {
        for (int i = 1; i <= n; i++) {
            for (int j = 1; j <= n; j++) {
                grid[i][j] = min(grid[i][j], grid[i][k] + grid[k][j]);
            }
        }
    }
    int z, start, end;
    cin >> z;
    while (z--) {
        cin >> start >> end;
        if (grid[start][end] == 10005) cout << -1 << endl;
        else cout << grid[start][end] << endl;
    }
}

A * 算法精讲(A star算法)

127. 骑士的攻击 (kamacoder.com)

#include
#include
#include

using namespace std;

int moves[1001][1001];
int dir[8][2]={-2,-1,-2,1,-1,2,1,2,2,1,2,-1,1,-2,-1,-2};
int b1, b2;

struct Knight{
    int x,y;
    int g,h,f;
    bool operator < (const Knight & k) const{  
     return k.f < f;
    }
};

priority_queue que;

int Heuristic(const Knight& k) { 
    return (k.x - b1) * (k.x - b1) + (k.y - b2) * (k.y - b2); 
}
void astar(const Knight& k)
{
    Knight cur, next;
	que.push(k);
	while(!que.empty())
	{
		cur=que.top(); que.pop();
		if(cur.x == b1 && cur.y == b2)
		break;
		for(int i = 0; i < 8; i++)
		{
			next.x = cur.x + dir[i][0];
			next.y = cur.y + dir[i][1];
			if(next.x < 1 || next.x > 1000 || next.y < 1 || next.y > 1000)
			continue;
			if(!moves[next.x][next.y])
			{
				moves[next.x][next.y] = moves[cur.x][cur.y] + 1;

				next.g = cur.g + 5;
                next.h = Heuristic(next);
                next.f = next.g + next.h;
                que.push(next);
			}
		}
	}
}

int main()
{
    int n, a1, a2;
    cin >> n;
    while (n--) {
        cin >> a1 >> a2 >> b1 >> b2;
        memset(moves,0,sizeof(moves));
        Knight start;
        start.x = a1;
        start.y = a2;
        start.g = 0;
        start.h = Heuristic(start);
        start.f = start.g + start.h;
		astar(start);
        while(!que.empty()) que.pop(); 
		cout << moves[b1][b2] << endl;
	}
	return 0;
}