HDU 1015 Safecracker

破解密码

把字符串从大到小排序，5个循环，验证目标函数

a-b*b+c*c*c-d*d*d*d+e*e*e*e*e == m为真时得到字符串 结束循环  输出

 1 #include <iostream>
 2 #include <cstring>
 3 #include <cstdio>
 4 #include <cstdlib>
 5 using namespace std;
 6 
 7 int compare(const void*a,const void*b){
 8     return *(char*)b-*(char*)a;
 9 }
10 int tar(int a,int b,int c,int d,int e,int m){
11     if(a-b*b+c*c*c-d*d*d*d+e*e*e*e*e == m)
12         return 1;
13     return 0;
14 }
15 int main()
16 {
17     int m,j1,j2,j3,j4,j5,flag;
18     char c[30],s[6];
19     int a[30];
20     while(~scanf("%d %s",&m,c) && m && strcmp(c,"END")){
21         memset(a,0,sizeof(a));
22         flag=0;
23         int lc=strlen(c);
24         qsort(c,lc,sizeof(c[0]),compare);
25         for(int i=0;i<lc;i++){
26             a[i]=c[i]-'A'+1;
27         }
28         for(j1=0;j1<lc;j1++){
29             for(j2=0;j2<lc;j2++){
30                 if(j2 == j1)
31                     continue;
32                 else for(j3=0;j3<lc;j3++){
33                     if(j3==j1 || j3==j2)
34                         continue;
35                     else for(j4=0;j4<lc;j4++){
36                         if(j4==j3 || j4==j2 ||j4==j1)
37                             continue;
38                         else for(j5=0;j5<lc;j5++){
39                             if(j5==j4 || j5==j3 || j5==j2 || j5==j1)
40                                 continue;
41                             else if(tar(a[j1],a[j2],a[j3],a[j4],a[j5],m) == 1){
42                                 flag = 1;s[0]=c[j1];s[1]=c[j2];s[2]=c[j3];s[3]=c[j4];s[4]=c[j5];s[5]='\0';
43                                 j1=lc;//修改最外层的循环变量结束循环
44                             }
45                         }
46                     }
47                 }
48             }
49         }
50         if(flag==0)printf("no solution\n");
51         else puts(s);
52     }
53     return 0;
54 }