HDU 1072 NYOJ 483 Nightmare -- BFS+允许回头

/*有两种做法：一个不考虑走了回头路，因为数据是在是小，几乎不浪费时间另一个是用贪心策略，先假设所有点剩余时间为0，只要该点剩余时间小于 上一点剩余时间-1 则修改remain值为remain-1再入队，否则不入队*/#include <iostream>#include <cstring>#include <cstdio>#include <queue>#include <algorithm>using namespace std;#define CLR(c,v) (memset(c,v,sizeof(c)))const int M         = 30;const int wall      = 0;const int road      = 1;const int start     = 2;const int end       = 3;const int reset     = 4;const int bomblimit = 6;int revise[][2]     = {{-1,0},       {0,-1},{0,1},          {1,0}};int map[M][M];int limit[M][M];int n,m; // n*mstruct _P{int x,y;int step,remain;_P(int x=-1,int y=-1,int step=0,int remain=0):x(x),y(y),step(step),remain(remain){}bool operator <(const _P& p){return step > p.step;}bool operator ==(const _P& p){return (x==p.x) && (y==p.y);}}S,E;typedef _P NEXT;typedef _P NOW;int BFS(){queue<_P> que;que.push(S);while(!que.empty()){NOW now = que.front();que.pop();if (now == E){return now.step;}for (int i = 0 ; i < 4 ; i++){int nx = now.x + revise[i][0];int ny = now.y + revise[i][1];int re = now.remain - 1;if ( !(nx >= 0 && nx < n && ny >= 0 && ny < m ) || re <= 0)continue; // 出界 或 时间耗尽if (map[nx][ny] == wall)continue;NEXT next = NEXT( nx, ny, now.step+1, re );if (map[nx][ny] == reset){next.remain = bomblimit;}if (limit[nx][ny] < next.remain){ // 只有当剩余时间发现-1之后 还长的 才入队limit[nx][ny] = next.remain;que.push(next);}}}return -1;}int main(){//freopen("in.txt","r",stdin);//freopen("Input.txt","r",stdin);//freopen("out.txt","w",stdout);int Ncase,g;cin >> Ncase;while(Ncase -- ){cin >> n >> m;CLR(limit,0);for (int i = 0 ; i <n ; i ++){for  (int j = 0 ; j < m ; j++){scanf("%d",&g);map[i][j] = g;//limit[i][j] = 0; // 初始化if (g == start){S = _P(i,j,0,bomblimit);limit[i][j] = bomblimit;}else if(g == end){E = _P(i,j,0,0);map[i][j] = road;}}}cout << BFS() << endl;}return 0;}/* 一些变态的数据,不符合input138 82 1 1 1 1 1 1 11 1 1 1 1 1 1 11 4 1 1 1 1 1 11 1 1 1 1 1 1 11 1 1 1 1 1 1 11 1 1 4 1 1 4 11 1 1 1 1 1 1 11 1 1 1 1 1 1 34 42 1 1 11 1 1 11 1 4 11 1 1 320 204 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 44 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 44 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 44 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 44 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 44 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 44 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 44 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 44 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 44 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 44 4 4 4 4 4 4 4 4 2 4 4 4 4 4 4 4 4 4 44 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 44 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 44 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 44 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 44 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 44 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 44 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 44 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 44 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 35 81 2 1 1 1 1 1 4 1 0 0 0 1 0 0 1 1 4 1 0 1 1 0 1 1 0 0 0 0 3 0 1 1 1 4 1 1 1 1 1 2 82 1 1 1 1 1 1 00 0 1 4 1 1 1 38 82 4 4 4 4 4 4 44 4 4 4 4 4 4 44 4 4 4 4 4 4 44 4 4 4 4 4 4 44 4 4 4 4 4 4 44 4 4 4 4 4 4 44 4 4 4 4 4 4 44 4 4 4 4 4 4 32 12 33 32 1 11 1 01 1 34 82 1 1 0 1 1 1 01 0 4 1 1 0 4 11 0 0 0 0 0 0 11 1 1 4 1 1 1 31 22 33 32 4 11 4 11 4 31 82 4 4 4 4 4 4 31 82 0 0 0 0 0 0 38 82 1 0 0 0 0 0 01 4 1 0 0 0 0 00 1 4 1 0 0 0 00 0 1 4 1 0 0 00 0 0 1 4 1 0 00 0 0 0 1 4 1 00 0 0 0 0 1 4 10 0 0 0 0 0 1 38 82 1 4 4 0 0 0 01 0 1 0 0 0 0 00 1 4 1 0 4 0 04 0 1 0 1 0 0 00 0 1 1 4 1 1 40 0 4 0 1 0 1 00 0 0 0 0 1 1 10 0 0 0 4 0 1 3*/