Meteor shower (POJ-3669)

The input part of the problem, write a wrong symbol, the result of various WA, really should not, since write once should be careful, strive to succeed.

Idea: Use the VIS array to record the most recent time each point was bombed by a bomb. Records the current time with the D array. When D<vis, this road can go, then the VIS initialization-1, when encountered Vis=-1, that is, the security zone.

Of course, the array should be slightly larger because the bombs will spread around.

#include <cstdio> #include <cstring> #include <iostream> #include <algorithm> #include <    Queue> #include <cmath>using namespace std;    int m;    int d[305][305];    int vis[305][305];    int dx[] = {1,0,-1,0,0};    int dy[] = {0,1,0,-1,0};        struct PA {int x, y;    PA (int x=0,int y=0): X (x), Y (y) {}};        int BFs () {queue<pa> q;        Q.push (PA (0,0));        Memset (d,-1,sizeof (d));        D[0][0] = 0;        if (Vis[0][0]==-1) return 0;        if (vis[0][0]==0) return-1;            while (!q.empty ()) {pa u = q.front (); Q.pop ();                for (int i=0;i<5;i++) {PA v;                v.x = U.x+dx[i];                V.Y = U.y+dy[i];                bool OK = false; if (v.x<0| |                V.Y&LT;0) continue;                if (d[v.x][v.y]==-1) {D[V.X][V.Y] = D[u.x][u.y] + 1; ok =true;}                if (vis[v.x][v.y]==-1) {return D[V.X][V.Y]; } if (Ok& &vis[v.x][v.y]>d[v.x][v.y]) Q.push (v);    }} return-1;        } int main () {scanf ("%d", &m);        memset (vis,-1,sizeof (VIS));        int x,y,t;            for (int i=0;i<m;i++) {scanf ("%d%d%d", &x,&y,&t);            if (vis[x][y]==-1) vis[x][y] = t;            else if (vis[x][y]>t) vis[x][y] = t;                if (x>0) {if (vis[x-1][y]==-1) vis[x-1][y] = t;            else if (vis[x-1][y]>t) vis[x-1][y] = t;                } if (y>0) {if (vis[x][y-1]==-1) vis[x][y-1] = t;            else if (vis[x][y-1]>t) vis[x][y-1] = t;            } if (vis[x+1][y]==-1) vis[x+1][y] = t;            else if (vis[x+1][y]>t) vis[x+1][y] = t;            if (vis[x][y+1]==-1) vis[x][y+1] = t;        else if (vis[x][y+1]>t) vis[x][y+1] = t;        } printf ("%d\n", BFS ());    return 0; }

Meteor shower (POJ-3669)