P1032 字串变换

 1 #include <math.h>
 2 #include <stdio.h>
 3 #include <stdlib.h>
 4 #include <iostream>
 5 #include <algorithm>
 6 #include <string>
 7 #include <string.h>
 8 #include <vector>
 9 #include <map>
10 #include <stack>
11 #include <set>
12 #include <queue>
13 
14 
15 #define LL long long
16 #define INF 0x3f3f3f3f
17 #define ls nod<<1
18 #define rs (nod<<1)+1
19 const int maxn = 20;
20 const double eps = 1e-9;
21 
22 struct Node {
23     std::string str;
24     int step;
25 };
26 
27 int cnt,n;
28 
29 std::string a,b;
30 std::string ori[maxn],trans[maxn];
31 std::map<std::string,int> mp;
32 
33 std::string tra(std::string str,int i,int j) {
34     std::string ans = "";
35     if (i+ori[j].length() > str.length()) {  // 说明后面没有ori[j].length()的长度的字符
36         return ans;
37     }
38     for (int k=0;k<ori[j].length();k++) {
39         if (str[i+k] != ori[j][k]) {
40             return ans;
41         }
42     }
43     ans = str.substr(0,i);
44     ans += trans[j];
45     ans += str.substr(i+ori[j].length());
46     return ans;
47 }
48 
49 void bfs() {
50     std::queue<Node> q;
51     Node st;
52     st.step = 0;
53     st.str = a;
54     q.push(st);
55     while (!q.empty()) {
56         Node ed = q.front();
57         q.pop();
58         std::string temp;
59         if (mp.count(ed.str) == 1) {
60             continue;
61         }
62         if (ed.str == b) {
63             cnt = ed.step;
64             break;
65         }
66         mp[ed.str] = 1;
67         for (int i=0;i<ed.str.length();i++) {
68             for (int j=0;j<n;j++) {
69                 temp = tra(ed.str,i,j);
70                 if (temp != "") {
71                     Node u;
72                     u.str = temp;
73                     u.step = ed.step + 1;
74                     q.push(u);
75                 }
76             }
77         }
78     }
79     if (cnt > 10 || cnt == 0) {
80         printf("NO ANSWER!\n");
81     }
82     else
83         printf("%d\n",cnt);
84 }
85 
86 int main() {
87     //freopen("../in.txt","r",stdin);
88     std::cin >> a >> b;
89     while (std::cin >> ori[n] >> trans[n])
90         n++;
91     bfs();
92     return 0;
93 }