uestc 851 方老师与素数

看了大牛的代码

新技能get√

如何优雅的计算广搜的次数

 1 #include<cstdio>

 2 #include<cstring>

 3 #include<cstring>

 4 #include<algorithm>

 5 #include<iostream>

 6 #include<queue>

 7 #include<string>

 8 #include<cmath>

 9 using namespace std;

10 #define MAXN 10001

11 

12 bool prime[MAXN];

13 int vis[MAXN];

14 int a, b, t;

15 

16 void deal()

17 {

18     for (int i = 2; i <= MAXN; ++i)

19         if (!prime[i])

20             for (int j = i*i; j <= MAXN; j += i)

21                 prime[j] = true;

22     /*for (int i = 0; i < 50; ++i)

23         if (!prime[i]) cout << i << " ";

24     cout << endl;*/

25 }

26 

27 int bfs()

28 {

29     queue<int> q;

30     q.push(a);

31     q.push(-1);

32     int ans = 0;

33     while (!q.empty()) {

34         int t = q.front();

35         if (t == -1) {

36             q.pop();

37             if (q.empty()) return -1;

38             ans++;

39             q.push(t); continue;

40         }q.pop();

41         if (t == b) return ans;

42         int s;

43         for (int i = 1; i <= 9; ++i) {

44             s = i * 1000 + t % 1000;

45             if (!vis[s] && !prime[s]) {

46                 q.push(s);

47                 vis[s] = true;

48             }

49         }

50         for (int i = 0; i <= 9; ++i) {

51             s = i * 100 + t % 100 + t/1000*1000;

52             if (!vis[s] && !prime[s]) {

53                 q.push(s);

54                 vis[s] = true;

55             }

56         }

57         for (int i = 0; i <= 9; ++i) {

58             s = i * 10 + t % 10 + t/100*100;

59             if (!vis[s] && !prime[s]) {

60                 q.push(s);

61                 vis[s] = true;

62             }

63         }

64         for (int i = 0; i <= 9; ++i) {

65             s = i + t / 10 * 10;

66             if (!vis[s] && !prime[s]) {

67                 q.push(s);

68                 vis[s] = true;

69             }

70         }

71     }

72     return -1;

73 }

74 

75 int main()

76 {

77     int  t;

78     cin >> t;

79     deal();

80     while (t--) {

81         cin >> a >> b;

82         memset(vis,0,sizeof(vis));

83         int res = bfs();

84         if (res == -1) puts("Impossible");

85         else cout << res << endl; 

86     }

87     return 0;

88 }