洛谷 P1126 机器人搬重物

机器人搬重物

坑点极多的一道bfs好题！

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <queue>
using namespace std;
//Mystery_Sky
//
#define INF 0x3f3f3f3f
const int M = 100;
struct node{
    int x, y, step, dirt, turn;//dirt取值为1， 2， 3， 4时别表示东，西，南，北。 
    node (int xx, int yy, int ss, int dd, int tt) : x(xx), y(yy), step(ss), dirt(dd), turn(tt){}
};
queue <node> q;
int n, m, ans, x1, x2, y1, y2;
char to;
int dis[M][M], map[M][M];
bool vis[M][M];
inline void bfs(int x1, int y1, int x2, int y2, char to)
{
    int drt;
    if(to == 'E') drt = 1;
    else if(to == 'W') drt = 2;
    else if(to == 'S') drt = 3;
    else drt = 4;
    q.push(node(x1, y1, 0, drt, 0));
    while(!q.empty()) {
        node top = q.front();
        q.pop();
        int dx, dy;
        for(int i = 1; i <= 5; i++) {//i=4表示左转， i=5表示右转 
            if(i != 4 && i != 5) {
                drt = top.dirt;
                if(drt == 1) {
                    dx = top.x;
                    dy = top.y + i;
                }	
                else if(drt == 2) {
                    dx = top.x;
                    dy = top.y - i;
                }
                else if(drt == 3) {
                    dx = top.x + i;
                    dy = top.y;
                }
                else {
                    dx = top.x - i;
                    dy = top.y;
                }
                if(map[dx][dy] == 1) i = 3;
                if(dx <= 0 || dy <= 0 || dx > n || dy > n)	{
                    i = 3;
                    continue;
                }
                if(vis[dx][dy]) {
                    continue;
                }
                if(dx == x2 && dy == y2) {
                    dis[x2][y2] = top.step + 1;	
                    return;
                }
                dis[dx][dy] = min(top.step + 1, dis[dx][dy]);
                vis[dx][dy] = 1;
                q.push(node(dx, dy, top.step+1, drt, 0)); 
            }
            else if(i == 4){
                int t = top.turn;
                if(t > 2) continue;
                dx = top.x, dy = top.y;
                drt = top.dirt;
                if(drt == 1) drt = 4;
                else if(drt == 2) drt = 3;
                else if(drt == 3) drt = 1;
                else drt = 2;
                dis[dx][dy] = min(top.step + 1, dis[dx][dy]);
                vis[dx][dy] = 1;
                q.push(node(dx, dy, top.step + 1, drt, t+1)); 
            }
            else {
                int t = top.turn;
                if(t > 2) continue;
                dx = top.x, dy = top.y;
                drt = top.dirt;
                if(drt == 1) drt = 3;
                else if(drt == 2) drt = 4;
                else if(drt == 3) drt = 2;
                else drt = 1;
                dis[dx][dy] = min(top.step + 1, dis[dx][dy]);
                vis[dx][dy] = 1;
                q.push(node(dx, dy, top.step + 1, drt, t+1)); 
            }
        }
    }
    return;
}

int main() {
    int a;
    scanf("%d%d", &n, &m);
    for(int i = 1; i <= n; i++) 
        for(int j = 1; j <= m; j++) {
            scanf("%d", &a);
            if(a == 1) {
                vis[i][j] = vis[i][j+1] = vis[i+1][j] = vis[i+1][j+1] = 1;
                map[i][j] = map[i][j+1] = map[i+1][j] = map[i+1][j+1] = 1;
            }
        }
    n++, m++;
    for(int i = 1; i <= m; i++) vis[1][i] = vis[n][i] = 1;
    for(int i = 1; i <= n; i++) vis[i][1] = vis[i][m] = 1;
    scanf("%d%d%d%d", &x1, &y1, &x2, &y2);
    getchar();
    x1++, x2++, y1++, y2++;
    scanf("%c", &to);
    memset(dis, INF, sizeof(dis));
    if(vis[x1][y1] || vis[x2][y2]) return 0 * printf("-1\n");
    if(x1 == x2 && y1 == y2) return 0 * printf("0\n");
    bfs(x1, y1, x2, y2, to);
//    for(int i = 1; i <= n; i++){
//    	for(int j = 1; j <= m; j++){
//    		if(dis[i][j] == INF) printf("-1 ");
//    		else printf("%d ", dis[i][j]);
//		}
//		printf("\n");
//	}
    if(dis[x2][y2] == INF) printf("-1\n");
    else printf("%d\n", dis[x2][y2]);
    return 0;
}