不仅仅是DFS，还需要考虑可以走到终点。同时，需要进行预处理。至多封闭点数为起点和终点的非墙壁点的最小值。
1 #include <iostream>
2 #include <cstdio>
3 #include <cstring>
4 #include <cstdlib>
5 #include <queue>
6 using namespace std;
7
8 typedef struct node_st {
9 int x, y, t, flg;
10 node_st() {}
11 node_st(int xx, int yy, int tt, int fflg) {
12 x=xx; y=yy; t=tt; flg=fflg;
13 }
14 } node_st;
15
16 char map[10][10];
17 char visit[10][10][2];
18 int direct[4][2] = {{-1,0},{1,0},{0,-1},{0,1}};
19 int n, m, time, fmin;
20 int begx, begy, endx, endy;
21
22 bool check(int x, int y) {
23 if (x<0 || x>=n || y<0 || y>= m)
24 return false;
25 return true;
26 }
27
28 bool bfs() {
29 queue<node_st> que;
30 int x, y, t, flg;
31 int i;
32 node_st node;
33
34 memset(visit, 0, sizeof(visit));
35 que.push(node_st(begx, begy, 0, 0));
36 visit[begx][begy][0] = 1;
37
38 while ( !que.empty() ) {
39 node = que.front();
40 que.pop();
41 t = node.t;
42 if (t == time)
43 break;
44 for (i=0; i<4; ++i) {
45 x = node.x + direct[i][0];
46 y = node.y + direct[i][1];
47 flg = node.flg;
48 if ( !check(x, y) )
49 continue;
50 if (map[x][y] != ‘#‘) {
51 if (map[x][y] == ‘E‘ && flg==1)
52 return true;
53 if (map[x][y] == ‘J‘)
54 flg = 1;
55 if (t<time && !visit[x][y][flg]) {
56 visit[x][y][flg] = 1;
57 que.push(node_st(x, y, t+1, flg));
58 }
59 }
60 }
61 }
62
63 return false;
64 }
65
66 void printmap() {
67 for (int i=0; i<n; ++i)
68 printf("\t%s\n", map[i]);
69 }
70
71 int dfs(int t, int cur) {
72 int flg = 0;
73 char ch;
74
75 if (t >= fmin)
76 return 0;
77
78 for (int i=0; i<n; ++i) {
79 for (int j=0; j<m; ++j) {
80 if (map[i][j]==‘.‘ || map[i][j] == ‘J‘) {
81 ch = map[i][j];
82 map[i][j] = ‘#‘;
83 if (cur == t) {
84 //printmap();
85 if ( !bfs() ) {
86 fmin = (t<fmin) ? t:fmin;
87 return 1;
88 }
89 }
90 if (cur < t)
91 flg = dfs(t, cur+1);
92 map[i][j] = ch;
93 }
94 if (flg)
95 return 1;
96 }
97 }
98
99 return 0;
100 }
101
102 int pre() {
103 int i, x, y, tmp1, tmp2;
104
105 tmp1 = 0;
106 for (i=0; i<4; ++i) {
107 x = begx + direct[i][0];
108 y = begy + direct[i][1];
109 if ( check(x, y) && (map[x][y]==‘.‘||map[x][y]==‘J‘))
110 tmp1++;
111 }
112
113 tmp2 = 0;
114 for (i=0; i<4; ++i) {
115 x = endx + direct[i][0];
116 y = endy + direct[i][1];
117 if ( check(x, y) && (map[x][y]==‘.‘||map[x][y]==‘J‘))
118 tmp2++;
119 }
120
121 return tmp1<tmp2 ? tmp1 : tmp2;
122 }
123
124 int main() {
125 int case_n;
126 int i, j;
127
128 scanf("%d", &case_n);
129
130 while (case_n--) {
131 scanf("%d %d %d%*c", &n, &m, &time);
132 for (i=0; i<n; ++i) {
133 scanf("%s", map[i]);
134 for (j=0; j<m; ++j) {
135 if (map[i][j] == ‘S‘) {
136 begx = i;
137 begy = j;
138 }
139 if (map[i][j] == ‘E‘) {
140 endx = i;
141 endy = j;
142 }
143 }
144 }
145 if ( !bfs() ) {
146 printf("0\n");
147 continue;
148 }
149 fmin = pre();
150 //printf("pre:%d\n", fmin);
151 dfs(1,1);
152 //printf("1:%d\n", fmin);
153 dfs(2,1);
154 //printf("2:%d\n", fmin);
155 dfs(3,1);
156 printf("%d\n", fmin);
157 }
158
159 return 0;
160 }
【HDOJ】1983 Kaitou Kid - The Phantom Thief (2)
时间： 2024-10-10 07:16:48