最大的位或

  1 #include <stdio.h>  2 #include <string.h>  3   4 typedef long long LL;  5   6 LL l,r,Max;  7 char bit_l[300];  8 char bit_r[300];  9 char temp[300]; 10  11 LL StrToNum(char s[])//二进制字符变数字 12 { 13     int len=strlen(s); 14     LL ans=0,res=1; 15     for (int i=len-1;i>=0;i--) 16     { 17         if (s[i]==‘1‘) 18             ans+=res; 19         res*=2; 20     } 21     return ans; 22 } 23  24 void NumToStr(LL x)//数字变二进制字符串 25 { 26     if (x==0) 27     { 28         temp[0]=‘0‘; 29         temp[1]=‘\0‘; 30         return ; 31     } 32     char s[300]; 33     int pos=0; 34     while (x!=0) 35     { 36         int tt=x%2; 37         if (tt==1) 38             s[pos++]=‘1‘; 39         else if (tt==0) 40             s[pos++]=‘0‘; 41         x/=2; 42     } 43     s[pos]=‘\0‘; 44     int i; 45     for (i=0;i<pos;i++) 46         temp[i]=s[pos-1-i]; 47     temp[i]=‘\0‘; 48 } 49  50 int main() 51 { 52     int i,j,t; 53     char test[300]; 54     scanf("%d",&t); 55     while (t--) 56     { 57         Max=-100; 58         scanf("%I64d%I64d",&l,&r); 59         if (l==r) 60         { 61             printf("%lld\n",l|r); 62             continue; 63         } 64         NumToStr(l); 65         strcpy(bit_l,temp); 66         NumToStr(r); 67         strcpy(bit_r,temp); 68  69         strcpy(test,bit_r); 70         int len_l=strlen(bit_l); 71         int len_r=strlen(bit_r); 72         for (i=0;i<len_r-len_l;i++) 73         { 74             test[i]=‘0‘; 75         } 76         for (j=0;j<=len_l;j++) 77         { 78             test[i++]=bit_l[j]; 79         } 80         strcpy(bit_l,test); 81         for (i=0;i<len_r;i++) 82         { 83             if (bit_l[i]==‘1‘||bit_r[i]==‘1‘) 84                 test[i]=‘1‘; 85             else 86                 test[i]=‘0‘; 87         } 88         test[i]=‘\0‘; 89         LL res; 90         res=StrToNum(test); 91         if (res>Max) Max=res; 92         //printf("l : %s\n",bit_l); 93         //printf("r : %s\n",bit_r); 94         //printf("t : %s\n",test); 95         int k=0; 96         while (bit_l[k]==bit_r[k]) k++; 97         k++; 98         for (i=k;i<len_r;i++) 99         {100             res=StrToNum(test);101             if (res>Max) Max=res;102             if (bit_l[i]==‘0‘&&bit_r[i]==‘0‘)103             {104                 test[i]=‘1‘;105                 res=StrToNum(test);106                 if (res>Max)107                     Max=res;108             }109         }110         printf("%I64d\n",Max);111     }112     return 0;113 }