题目链接：http://hihocoder.com/problemset/problem/1328
这个题bfs到时候不止要存当前的坐标，还要存当前有哪几把钥匙。因为5把钥匙，所以可以直接用位来存，这样也可以解决一个房间里有好几把钥匙的情况。
还有就是走的过程中，一个点重复走多少次的问题，我们用vis(x,y,k)来记录坐标(x,y)的时候拿着钥匙位压后为k的情况，并且初始化成0x7f7f7f，每次更新最短路，假如有重复走并且拥有钥匙情况相同的情况就可以剪掉了。
1 /*
2 ━━━━━┒ギリギリ♂ eye！
3 ┓┏┓┏┓┃キリキリ♂ mind！
4 ┛┗┛┗┛┃＼○／
5 ┓┏┓┏┓┃ /
6 ┛┗┛┗┛┃ノ)
7 ┓┏┓┏┓┃
8 ┛┗┛┗┛┃
9 ┓┏┓┏┓┃
10 ┛┗┛┗┛┃
11 ┓┏┓┏┓┃
12 ┛┗┛┗┛┃
13 ┓┏┓┏┓┃
14 ┃┃┃┃┃┃
15 ┻┻┻┻┻┻
16 */
17 #include <algorithm>
18 #include <iostream>
19 #include <iomanip>
20 #include <cstring>
21 #include <climits>
22 #include <complex>
23 #include <cassert>
24 #include <cstdio>
25 #include <bitset>
26 #include <vector>
27 #include <deque>
28 #include <queue>
29 #include <stack>
30 #include <ctime>
31 #include <set>
32 #include <map>
33 #include <cmath>
34 using namespace std;
35 #define fr first
36 #define sc second
37 #define cl clear
38 #define BUG puts("here!!!")
39 #define W(a) while(a--)
40 #define pb(a) push_back(a)
41 #define Rint(a) scanf("%d", &a)
42 #define Rll(a) scanf("%I64d", &a)
43 #define Rs(a) scanf("%s", a)
44 #define Cin(a) cin >> a
45 #define FRead() freopen("in", "r", stdin)
46 #define FWrite() freopen("out", "w", stdout)
47 #define Rep(i, len) for(int i = 0; i < (len); i++)
48 #define For(i, a, len) for(int i = (a); i < (len); i++)
49 #define Cls(a) memset((a), 0, sizeof(a))
50 #define Clr(a, x) memset((a), (x), sizeof(a))
51 #define Full(a) memset((a), 0x7f7f, sizeof(a))
52 #define lrt rt << 1
53 #define rrt rt << 1 | 1
54 #define pi 3.14159265359
55 #define RT return
56 #define lowbit(x) x & (-x)
57 #define onenum(x) __builtin_popcount(x)
58 typedef long long LL;
59 typedef long double LD;
60 typedef unsigned long long ULL;
61 typedef pair<int, int> pii;
62 typedef pair<string, int> psi;
63 typedef pair<LL, LL> pll;
64 typedef map<string, int> msi;
65 typedef vector<int> vi;
66 typedef vector<LL> vl;
67 typedef vector<vl> vvl;
68 typedef vector<bool> vb;
69
70 typedef struct Node {
71 int x, y;
72 int s;
73 int k;
74 Node() {}
75 Node(int xx, int yy, int ss, int kk) : x(xx), y(yy), s(ss), k(kk) {}
76 }Node;
77 const int dx[5] = {1,-1,0,0};
78 const int dy[5] = {0,0,1,-1};
79 const int maxn = 110;
80 int n, m, k;
81 int sx, sy, ex, ey;
82 int vis[maxn][maxn][33];
83 char G[maxn][maxn];
84 char ks[maxn][maxn];
85 int ret;
86 queue<Node> q;
87
88 bool ok(int x, int y) {
89 return x >= 0 && y >= 0 && x < n && y < m && G[x][y] != ‘#‘;
90 }
91
92 bool yes(int x, int y, int k) {
93 if(G[x][y] == ‘.‘) return 1;
94 return k & (1 << (G[x][y] - ‘A‘));
95 }
96
97 void bfs() {
98 while(!q.empty()) q.pop();
99 q.push(Node(sx, sy, 0, 0));
100 vis[sx][sy][0] = 0;
101 while(!q.empty()) {
102 Node t = q.front(); q.pop();
103 // printf("%d\n", t.k);
104 if(t.x == ex && t.y == ey) {
105 ret = min(ret, t.s);
106 return;
107 }
108 Rep(i, 4) {
109 int x = t.x + dx[i];
110 int y = t.y + dy[i];
111 if(ok(x, y)) {
112 int ck = t.k | ks[x][y];
113 if(vis[x][y][ck] > t.s + 1 && yes(x, y, ck)) {
114 vis[x][y][ck] = t.s + 1;
115 q.push(Node(x, y, t.s+1, ck));
116 }
117 }
118 }
119 }
120 }
121
122 int main() {
123 // FRead();
124 int x, y;
125 while(~scanf("%d%d%d%d%d%d%d",&n,&m,&k,&sx,&sy,&ex,&ey)) {
126 Clr(vis, 0x7f7f); Cls(G); Cls(ks); ret = 0x7f7f;
127 Rep(i, n) Rs(G[i]);
128 Rep(i, k) {
129 Rint(x); Rint(y);
130 ks[x][y] |= (1 << i);
131 }
132 bfs();
133 if(ret != 0x7f7f) printf("%d\n", ret);
134 else printf("-1\n");
135 }
136 RT 0;
137 }
这种判断重复的方法是不对的，因为会在一个出不去而不停兜圈子，拿不到钥匙并且会超时。
1 /*
2 ━━━━━┒ギリギリ♂ eye！
3 ┓┏┓┏┓┃キリキリ♂ mind！
4 ┛┗┛┗┛┃＼○／
5 ┓┏┓┏┓┃ /
6 ┛┗┛┗┛┃ノ)
7 ┓┏┓┏┓┃
8 ┛┗┛┗┛┃
9 ┓┏┓┏┓┃
10 ┛┗┛┗┛┃
11 ┓┏┓┏┓┃
12 ┛┗┛┗┛┃
13 ┓┏┓┏┓┃
14 ┃┃┃┃┃┃
15 ┻┻┻┻┻┻
16 */
17 #include <algorithm>
18 #include <iostream>
19 #include <iomanip>
20 #include <cstring>
21 #include <climits>
22 #include <complex>
23 #include <cassert>
24 #include <cstdio>
25 #include <bitset>
26 #include <vector>
27 #include <deque>
28 #include <queue>
29 #include <stack>
30 #include <ctime>
31 #include <set>
32 #include <map>
33 #include <cmath>
34 using namespace std;
35 #define fr first
36 #define sc second
37 #define cl clear
38 #define BUG puts("here!!!")
39 #define W(a) while(a--)
40 #define pb(a) push_back(a)
41 #define Rint(a) scanf("%d", &a)
42 #define Rll(a) scanf("%I64d", &a)
43 #define Rs(a) scanf("%s", a)
44 #define Cin(a) cin >> a
45 #define FRead() freopen("in", "r", stdin)
46 #define FWrite() freopen("out", "w", stdout)
47 #define Rep(i, len) for(int i = 0; i < (len); i++)
48 #define For(i, a, len) for(int i = (a); i < (len); i++)
49 #define Cls(a) memset((a), 0, sizeof(a))
50 #define Clr(a, x) memset((a), (x), sizeof(a))
51 #define Full(a) memset((a), 0x7f7f7f, sizeof(a))
52 #define lrt rt << 1
53 #define rrt rt << 1 | 1
54 #define pi 3.14159265359
55 #define RT return
56 #define lowbit(x) x & (-x)
57 #define onenum(x) __builtin_popcount(x)
58 typedef long long LL;
59 typedef long double LD;
60 typedef unsigned long long ULL;
61 typedef pair<int, int> pii;
62 typedef pair<string, int> psi;
63 typedef pair<LL, LL> pll;
64 typedef map<string, int> msi;
65 typedef vector<int> vi;
66 typedef vector<LL> vl;
67 typedef vector<vl> vvl;
68 typedef vector<bool> vb;
69
70 typedef struct Node {
71 int x, y;
72 int s;
73 int k;
74 Node() {}
75 Node(int xx, int yy, int ss) : x(xx), y(yy), s(ss) { k = 0; }
76 Node(int xx, int yy, int ss, int kk) : x(xx), y(yy), s(ss), k(kk) {}
77 }Node;
78 const int dx[5] = {1,-1,0,0};
79 const int dy[5] = {0,0,1,-1};
80 const int maxn = 110;
81 int n, m, k;
82 int sx, sy, ex, ey;
83 char G[maxn][maxn];
84 char ks[maxn][maxn];
85 int ret;
86 queue<Node> q;
87
88 bool ok(int x, int y) {
89 return x >= 0 && y >= 0 && x < n && y < m && G[x][y] != ‘#‘;
90 }
91
92 void bfs() {
93 while(!q.empty()) q.pop();
94 q.push(Node(sx, sy, 0, 0));
95 int wtf = 0;
96 while(!q.empty()) {
97 if(wtf++ == 9000000) return;
98 Node t = q.front(); q.pop();
99 // printf("%d\n", t.k);
100 if(t.x == ex && t.y == ey) {
101 ret = min(ret, t.s);
102 return;
103 }
104 Rep(i, 4) {
105 int x = t.x + dx[i];
106 int y = t.y + dy[i];
107 if(ok(x, y)) {
108 int cur = t.k | ks[x][y];
109 if(G[x][y] == ‘.‘ || (cur & (1 << (G[x][y] - ‘A‘)))) {
110 q.push(Node(x, y, t.s+1, cur));
111 }
112 }
113 }
114 }
115 }
116
117 int main() {
118 // FRead();
119 int x, y;
120 while(~scanf("%d%d%d%d%d%d%d",&n,&m,&k,&sx,&sy,&ex,&ey)) {
121 Cls(G); Cls(ks); ret = 0x7f7f7f;
122 Rep(i, n) Rs(G[i]);
123 Rep(i, k) {
124 Rint(x); Rint(y);
125 ks[x][y] |= (1 << i);
126 }
127 bfs();
128 if(ret == 0x7f7f7f) printf("-1\n");
129 else printf("%d\n", ret);
130 }
131 RT 0;
132 }
时间： 2024-10-17 16:46:38