HDU 1026 （BFS+记录路径）

BFS + 路径记录：

/*  *problem ID: HDU 1026 * Author ID: fuqiang11  *      TIME: 2013-07-17  * Algorithm: BFS   *    Status: (Accept) */  #include <iostream>#include <cstdio>#include <queue>using namespace std;#define INF 0x3f3f3f3f#define maxn 103char map[maxn][maxn];int N,M;int value[maxn][maxn];  //记录步数struct point{int x;int y;}st,ed,a,pre[maxn][maxn];  //pre 记录前一个点int xx[] = {1,-1,0,0};int yy[] = {0,0,1,-1};void bfs(int x,int y){memset(value,0x3f,sizeof(value));value[0][0] = 0;queue <point> q;st.x = x;st.y = y;q.push(st);while(!q.empty()){a = q.front();q.pop();for(int i = 0; i < 4; i++){ed.x = a.x + xx[i];ed.y = a.y + yy[i];if(ed.x<0||ed.x>N-1||ed.y<0||ed.y>M-1||map[ed.x][ed.y]=='X')continue;if(map[ed.x][ed.y]=='.'){if(value[a.x][a.y] + 1 < value[ed.x][ed.y]){value[ed.x][ed.y] = value[a.x][a.y] + 1;pre[ed.x][ed.y].x = a.x;pre[ed.x][ed.y].y = a.y;q.push(ed);}}else{if(value[a.x][a.y] + map[ed.x][ed.y] - '0' + 1 < value[ed.x][ed.y]){value[ed.x][ed.y] = value[a.x][a.y] + map[ed.x][ed.y] - '0' + 1;pre[ed.x][ed.y].x = a.x;pre[ed.x][ed.y].y = a.y;q.push(ed);}}}}}void prin_pre(int i, int j)  //输出路径{    if(pre[i][j].x == -1)        return ;    prin_pre(pre[i][j].x, pre[i][j].y);    if(map[i][j]=='.')        printf("%ds:(%d,%d)->(%d,%d)\n",value[i][j],pre[i][j].x,pre[i][j].y,i,j);    else    {        int num = map[i][j]-'0';        int t = value[i][j] - num;        printf("%ds:(%d,%d)->(%d,%d)\n",t++,pre[i][j].x,pre[i][j].y,i,j);        for(int k = 1; k <= num; k++)        {            printf("%ds:FIGHT AT (%d,%d)\n",t++,i,j);        }    }}int main(){while(scanf("%d%d",&N,&M)!=EOF){getchar();for(int i = 0; i < N; i++)gets(map[i]);pre[0][0].x = pre[0][0].y = -1;bfs(0,0);if(value[N-1][M-1]!=INF){printf("It takes %d seconds to reach the target position, let me show you the way.\n",value[N-1][M-1]);prin_pre(N-1,M-1);}else{printf("God please help our poor hero.\n");}puts("FINISH");}}

DFS超时（明显的，N、M <= 100，我居然还这样做的！）

如果N.M较小的话，还是能承受的，比如10、20、30

超时的代码先挂这吧，以示警醒；

/* *problem ID: HDU 1026 * Author ID: fuqiang11 *      TIME: 2013-07-16 * Algorithm: DFS  *    Status: (RunTimeError)*/#include <iostream>#include <cstdio>#include <cstring>#include <string>#define INF 0x3f3f3f3fusing namespace std;#define maxn 103char map[maxn][maxn];int v[maxn][maxn];struct Point{int x;int y;}pre[maxn][maxn];int N,M;int xplus[] = {1,-1,0,0};int yplus[] = {0,0,1,-1};void dfs(int x,int y){if(x==N-1 && y==M-1)return ;int xx,yy;for(int i = 0; i < 4; i++){xx = x + xplus[i];yy = y + yplus[i];if(xx<0 || xx>N-1 || yy<0 || yy>M-1)continue;if(map[xx][yy]=='.'){if(v[x][y] + 1 < v[xx][yy]){v[xx][yy] = v[x][y] + 1;pre[xx][yy].x = x;pre[xx][yy].y = y;dfs(xx,yy);}}if(map[xx][yy]>='1' && map[xx][yy]<='9'){if(v[x][y] + 1 + map[xx][yy] - '0' < v[xx][yy]){v[xx][yy] = v[x][y] + 1 + map[xx][yy] - '0';pre[xx][yy].x = x;pre[xx][yy].y = y; dfs(xx,yy);}}}}void prin_pre(int i, int j)  //输出路径{if(pre[i][j].x == -1)return ;prin_pre(pre[i][j].x, pre[i][j].y);if(map[i][j]=='.')printf("%ds:(%d,%d)->(%d,%d)\n",v[i][j],pre[i][j].x,pre[i][j].y,i,j);else{int num = map[i][j]-'0';int t = v[i][j] - num;printf("%ds:(%d,%d)->(%d,%d)\n",t++,pre[i][j].x,pre[i][j].y,i,j);for(int k = 1; k <= num; k++){printf("%ds:FIGHT AT (%d,%d)\n",t++,i,j);}}}int main(){while(scanf("%d%d",&N,&M)!=EOF){cin.get();for(int i = 0; i < N; i++)gets(map[i]);memset(v,0x3f,sizeof(v));v[0][0] = 0;pre[0][0].x = pre[0][0].y = -1;dfs(0,0);if(v[N-1][M-1] != INF){printf("It takes %d seconds to reach the target position, let me show you the way.\n",v[N-1][M-1]);prin_pre(N-1,M-1);}else{printf("God please help our poor hero.\n");}puts("FINISH");}}