[NBUT 1642 简单的图论问题?] dijkstra 模板

题目链接： [NBUT 1642 简单的图论问题?]

解题思路：第一个就是一个裸的最短路问题， 第二个答案就是一个三维的最短路。贴一个最短路模板

#include <queue>#include <cmath>#include <vector>#include <cstdio>#include <string>#include <cstring>#include <iostream>#include <algorithm>using namespace std;//#pragma comment(linker, "/STACK:1024000000,1024000000")#define FIN             freopen("input.txt","r",stdin)#define FOUT            freopen("output.txt","w",stdout)#define fst             first#define snd             secondtypedef __int64  LL;typedef pair<int, int> PII;const double eps = 1e-10;const int MAXN = 500 + 5;const int INF  = 0x3f3f3f3f;const int DIR[][2] = {{ -1, 0}, {1, 0}, {0, -1}, {0, 1}};int N, M, R1, C1, R2, C2;int maze[MAXN][MAXN];char buf[10];struct Dijstra1 {    struct QNode {        PII pnt;        int dis;        QNode() {}        QNode (PII pnt, int dis) : pnt (pnt), dis (dis) {}        bool operator > (const QNode &e) const {            return dis > e.dis;        }    };    int mincost[MAXN][MAXN];    bool vis[MAXN][MAXN];    QNode tp;    priority_queue<QNode, vector<QNode>, greater<QNode> > Q;    void init() {        memset (mincost, 0x3f, sizeof (mincost) );        memset (vis, false, sizeof (vis) );        while (!Q.empty() ) Q.pop();    }    void run (int sx, int sy) {        int x, y, nx, ny;        mincost[sx][sy] = maze[sx][sy];        Q.push (QNode (PII (sx, sy), mincost[sx][sy]) );        while (!Q.empty() ) {            tp = Q.top();            Q.pop();            x = tp.pnt.fst;            y = tp.pnt.snd;            if (vis[x][y]) continue;            vis[x][y] = true;            for (int i = 0; i < 4; i ++) {                nx = x + DIR[i][0];                ny = y + DIR[i][1];                if (nx > N || nx < 1 || ny > M || ny < 1) continue;                if (maze[nx][ny] == -1) continue;                if (mincost[nx][ny] > mincost[x][y] + maze[nx][ny]) {                    mincost[nx][ny] = mincost[x][y] + maze[nx][ny];                    Q.push (QNode (PII (nx, ny), mincost[nx][ny]) );                }            }        }    }} dij1;struct Dijstra2 {    struct QNode {        PII pnt;        int dis, dir;        QNode() {}        QNode (PII pnt, int dis) : pnt (pnt), dis (dis) {}        QNode (PII pnt, int dis, int dir) : pnt (pnt), dis (dis), dir (dir) {}        bool operator > (const QNode &e) const {            return dis > e.dis;        }    };    int mincost[MAXN][MAXN][4];    bool vis[MAXN][MAXN][4];    QNode tp;    priority_queue<QNode, vector<QNode>, greater<QNode> > Q;    void init() {        memset (mincost, 0x3f, sizeof (mincost) );        memset (vis, false, sizeof (vis) );        while (!Q.empty() ) Q.pop();    }    void run (int sx, int sy) {        int x, y, nx, ny;        for (int i = 0; i < 4; i++) {            mincost[sx][sy][i] = maze[sx][sy];            Q.push (QNode (PII (sx, sy), mincost[sx][sy][i], i) );        }        while (!Q.empty() ) {            tp = Q.top();            Q.pop();            x = tp.pnt.fst;            y = tp.pnt.snd;            if (tp.dir != -1 && vis[x][y][tp.dir]) continue;            if (tp.dir != -1) {                vis[x][y][tp.dir] = true;            }            for (int i = 0; i < 4; i ++) {                nx = x + DIR[i][0];                ny = y + DIR[i][1];                if (nx > N || nx < 1 || ny > M || ny < 1) continue;                if (maze[nx][ny] == -1) continue;                if (tp.dir == i) continue;                if (mincost[nx][ny][i] > mincost[x][y][tp.dir] + maze[nx][ny]) {                    mincost[nx][ny][i] = mincost[x][y][tp.dir] + maze[nx][ny];                    Q.push (QNode (PII (nx, ny), mincost[nx][ny][i], i) );                }            }        }    }} dij2;int main() {#ifndef ONLINE_JUDGE    FIN;    // FOUT;#endif // ONLINE_JUDGE    int cas = 0;    int res1, res2;    while (~scanf ("%d %d %d %d %d %d", &N, &M, &R1, &C1, &R2, &C2) ) {        for (int i = 1; i <= N; i ++) {            for (int j = 1; j <= M; j++) {                scanf ("%s", buf);                if (buf[0] == '*') {                    maze[i][j] = -1;                } else {                    maze[i][j] = atoi (buf);                }            }        }        dij1.init();        dij2.init();        dij1.run (R1, C1);        dij2.run (R1, C1);        res1 = dij1.mincost[R2][C2];        res2 = INF;        for (int i = 0; i < 4; i++) {            res2 = min (res2, dij2.mincost[R2][C2][i]);        }        if (res1 == INF) res1 = -1;        if (res2 == INF) res2 = -1;        printf ("Case %d: %d %d\n", ++cas, res1, res2);    }    return 0;}