Cod sursa(job #1654580)

Utilizator atatomirTatomir Alex atatomir Data 17 martie 2016 11:24:14
Problema Car Scor 80
Compilator cpp Status done
Runda Arhiva de probleme Marime 2.39 kb
/*
 * Dijkstra with low costs + compression
 */

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

using namespace std;

#define mp make_pair
#define pb push_back
#define ll long long

#define maxN 555
#define maxDir 9

int defX[8] = {+1, +1, +1, 0, -1, -1, -1, 0};
int defY[8] = {-1, 0, +1, +1, +1, 0, -1, -1};
int defAng[8] = {0, 1, 2, 3, 4, 5, 6, 7};

int n, m, i, j, x, y, dir;
int xs, ys, xd, yd;
bool deny[maxN][maxN];

int dist[maxN][maxN][maxDir];
vector<int> H[maxN * maxN * 4 + 10];
int h_cnt, h_pos;

int ans;

int compress(int x, int y, int dir) {
    return (x << 12) + (y << 3) + dir;
}

int decompress(int val, int &x, int &y, int &dir) {
    dir = val & 7;
    val >>= 3;

    y = val & 511;
    val >>= 9;

    x = val;
}


int pay(int ang1, int ang2) {
    ang1 -= ang2;
    if (ang1 < 0) ang1 = -ang1;
    if (ang1 > 4) ang1 = 8 - ang1;

    return ang1;
}



int main()
{
    freopen("car.in","r",stdin);
    freopen("car.out","w",stdout);

    scanf("%d%d", &n, &m);
    scanf("%d%d%d%d", &xs, &ys, &xd, &yd);

    for (i = 1; i <= n; i++) {
        for (j = 1; j <= m; j++) {
            scanf("%d", &x);
            if (x) deny[i][j] = true;
        }
    }

    for (i = 0; i <= n + 1; i++)
        deny[i][0] = deny[i][m + 1] = true;

    for (i = 0; i <= m + 1; i++)
        deny[0][i] = deny[n + 1][i] = true;


    //! start the engine
    for (i = 0; i < 8; i++) {
        dist[xs][ys][i] = 1;

        h_cnt++;
        H[1].pb(compress(xs, ys, i));
    }

    h_pos = 1;

    while (h_cnt) {
        while (H[h_pos].empty()) h_pos++;

        int now = H[h_pos][ H[h_pos].size() - 1 ];
        H[h_pos].pop_back();
        h_cnt--;

        decompress(now, x, y, dir);

        if (x == xd && y == yd) {
            ans = h_pos;
            break;
        }

        if (dist[x][y][dir] < h_pos) continue;
        for (i = 0; i < 8; i++) {
            int xx = x + defX[i];
            int yy = y + defY[i];
            int new_pay = dist[x][y][dir] + pay(dir, defAng[i]);

            if (deny[xx][yy]) continue;
            if (dist[xx][yy][i] == 0 || dist[xx][yy][i] > new_pay) {
                dist[xx][yy][i] = new_pay;

                H[new_pay].pb(compress(xx, yy, i));
                h_cnt++;
            }
        }
    }

    if (ans == 0)
        printf("-1");
    else
        printf("%d", ans - 1);


    return 0;
}