bfs+位压缩：
hdu 1429 http://acm.hdu.edu.cn/showproblem.php?pid=1429
中文题目：
思路：bfs+位压缩
#include <iostream> #include <cstdio> #include <cmath> #include <vector> #include <cstring> #include <algorithm> #include <string> #include <set> #include <functional> #include <numeric> #include <sstream> #include <stack> #include <map> #include <queue> #define CL(arr, val) memset(arr, val, sizeof(arr)) #define lc l,m,rt<<1 #define rc m + 1,r,rt<<1|1 #define pi acos(-1.0) #define L(x) (x) << 1 #define R(x) (x) << 1 | 1 #define MID(l, r) (l + r) >> 1 #define Min(x, y) (x) < (y) ? (x) : (y) #define Max(x, y) (x) < (y) ? (y) : (x) #define E(x) (1 << (x)) #define iabs(x) (x) < 0 ? -(x) : (x) #define OUT(x) printf("%I64d\n", x) #define lowbit(x) (x)&(-x) #define Read() freopen("din.txt", "r", stdin) #define Write() freopen("dout.txt", "w", stdout) #define M 137 #define N 22 using namespace std; const double eps = 1e-10; struct node { int x,y; int val; int msk;//一共10为来表示到达某点时所拥有的钥匙种类 bool operator < (const node &a) const { return val > a.val; } }nd; priority_queue<node>Q; int sx,sy,ex,ey; char mat[N][N]; int n,m,k; int dx[4] = {-1,0,1,0}; int dy[4] = {0,1,0,-1}; bool vt[N][N][1028];//由于是优先队列处理所以只要到达该点就是最优的 int bfs(int x,int y) { CL(vt,false); while (!Q.empty()) Q.pop(); nd.x = x; nd.y = y; nd.val = 0; nd.msk = 0; Q.push(nd); vt[x][y][nd.msk] = true; while (!Q.empty()) { node u = Q.top(); Q.pop(); for (int i = 0; i < 4; ++i) { int tx = u.x + dx[i]; int ty =u.y + dy[i]; int val = u.val + 1; int msk = u.msk; if (val >= k) continue; if (tx >= 0 && tx < n && ty >= 0 && ty < m && mat[tx][ty] != '*' && !vt[tx][ty][msk]) { nd.x = tx; nd.y = ty; nd.val = val; nd.msk = msk; if (mat[tx][ty] == '.' || mat[tx][ty] == '@') { vt[tx][ty][msk] = true; Q.push(nd); } else if (mat[tx][ty] >= 'a' && mat[tx][ty] <= 'j') { nd.msk = nd.msk | (1<<(mat[tx][ty] - 32 - 'A')); vt[tx][ty][nd.msk] = true; Q.push(nd); } else if (mat[tx][ty] >= 'A' && mat[tx][ty] <= 'J') { if (u.msk & (1<<(mat[tx][ty] - 'A'))) { vt[tx][ty][msk] = true; Q.push(nd); } } else if (mat[tx][ty] == '^') { return nd.val; } } } } return -1; } int main() { // Read(); int i,j; while (~scanf("%d%d%d",&n,&m,&k)) { for (i = 0; i < n; ++i) { scanf("%s",mat[i]); for (j = 0; j < m; ++j) { if (mat[i][j] == '@') { sx = i; sy = j; } } } printf("%d\n", bfs(sx,sy)); } return 0; }