ACM-ICPC North America Qualifier 2014 Eight Queens

题意：问图是否满足八皇后。

解题思路：hash，dp，位运算

解题代码：

我的搓代码。

 1 // File Name: a.cpp
 2 // Author: darkdream
 3 // Created Time: 2015年03月14日 星期六 12时00分44秒
 4
 5 #include<vector>
 6 #include<list>
 7 #include<map>
 8 #include<set>
 9 #include<deque>
10 #include<stack>
11 #include<bitset>
12 #include<algorithm>
13 #include<functional>
14 #include<numeric>
15 #include<utility>
16 #include<sstream>
17 #include<iostream>
18 #include<iomanip>
19 #include<cstdio>
20 #include<cmath>
21 #include<cstdlib>
22 #include<cstring>
23 #include<ctime>
24 #define LL long long
25
26 using namespace std;
27 char  str[10][10];
28 int hsh[10];
29 int hsl[10];
30 int hshl[50];
31 int hslh[50];
32 int main(){
33     while(scanf("%s",&str[1][1]) != EOF)
34     {
35        for(int i = 2;i <= 8 ;i ++)
36        {
37          scanf("%s",&str[i][1]);
38        }
39        memset(hsh,0,sizeof(hsh));
40        memset(hsl,0,sizeof(hsh));
41        memset(hshl,0,sizeof(hshl));
42        memset(hslh,0,sizeof(hslh));
43        int ok = 0 ;
44        for(int i= 1;i <= 8;i ++)
45        {
46           for(int j = 1;j <= 8 ;j ++)
47           {
48               if(str[i][j] == ‘.‘)
49                   continue;
50               if(hsh[i] == 1)
51               {
52                  ok = 1;
53               }else{
54                  hsh[i] = 1 ;
55               }
56
57               if(hsl[j] == 1)
58               {
59                  ok = 1;
60               }else{
61                  hsl[j] = 1 ;
62               }
63
64               if(hshl[j-i+25] == 1)
65               {
66                  ok = 1;
67               }else{
68                  hshl[j-i +25] = 1 ;
69               }
70
71               if(hslh[j+i] == 1)
72               {
73                  ok = 1;
74               }else{
75                  hslh[j+i] = 1 ;
76               }
77           }
78
79        }
80        if(ok == 1 )
81            printf("invalid\n");
82        else printf("valid\n");
83     }
84
85
86     return 0;
87 }

然后看到了学弟的位运算代码：

 1 #include <iostream>
 2 #include <vector>
 3 #include <cstdio>
 4 #include <cstring>
 5 using namespace std;
 6 char chess[10][10];
 7 int stu1 = 0, stu2 = 0, flag = 0;
 8 int main() {
 9     for (int i = 0; i < 8; i++)     gets (chess[i]);
10     for (int i = 0; i < 8; i++) {
11         for (int j = 0; j < 8; j++)
12             if (chess[i][j] == ‘*‘)
13                 if (! (stu1 & 1 << j) && ! (stu2 & 1 << j))
14                         stu1 |= 1 << j, stu2 |= 1 << j;
15                 else {
16                     flag = 1;break;
17                 }
18         if (flag) break;
19         stu1 <<= 1, stu2 >>= 1;
20     }
21     if(flag) puts("invalid");
22     else puts("valid");
23 }