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Very often, especially in programming contests, we treat a sequence of non-whitespace characters as a string. But sometimes, a string may contain whitespace characters or even be empty. We can have such strings quoted and escaped to handle these cases. However, a different approach is putting the length of the string before it. As most strings are short in practice, it would be a waste of space to encode the length as a 64-bit unsigned integer or add a extra separator between the length and the string. That‘s why a 7-bit encoded integer is introduced here.
To store the string length by 7-bit encoding, we should regard the length as a binary integer. It should be written out by seven bits at a time, starting with the seven least-significant (i.e. 7 rightmost) bits. The highest (i.e. leftmost) bit of a byte indicates whether there are more bytes to be written after this one. If the integer fits in seven bits, it takes only one byte of space. If the integer does not fit in seven bits, the highest bit is set to 1 on the first byte and written out. The integer is then shifted by seven bits and the next byte is written. This process is repeated until the entire integer has been written.
With the help of 7-bit encoded integer, we can store each string as a length-prefixed string by concatenating its 7-bit encoded length and its raw content (i.e. the original string).
There are multiple test cases. The first line of input is an integer T indicating the number of test cases.
Each test case is simply a string in a single line with at most 3000000 characters.
For each test case, output the corresponding length-prefixed string in uppercase hexadecimal. See sample for more details.
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023432 1779756B6B75726920736869746569747465206E65212121 9A0168747470733A2F2F656E2E77696B6970656469612E6F72672F77696B692F416E737765725F746F5F4C6966652C5F7468655F556E6976657273652C5F616E645F45766572797468696E6723416E737765725F746F5F7468655F556C74696D6174655F5175657374696F6E5F6F665F4C6966652E32435F7468655F556E6976657273655F616E645F45766572797468696E675F2E323834322E3239
1 #include <iostream> 2 #include <cstdio> 3 #include <cstring> 4 #include <cmath> 5 #include <algorithm> 6 #include <climits> 7 #include <vector> 8 #include <queue> 9 #include <cstdlib> 10 #include <string> 11 #include <set> 12 #define LL long long 13 #define INF 0x3f3f3f3f 14 using namespace std; 15 char str[3000100]; 16 int main(){ 17 int t,i,len; 18 scanf("%d",&t); 19 getchar(); 20 while(t--){ 21 gets(str); 22 len = strlen(str); 23 if(!len){puts("00");continue;} 24 while(len){ 25 int temp = len&127; 26 len >>= 7; 27 if(len) temp |= 128; 28 if(temp < 16) printf("0"); 29 printf("%X",temp); 30 } 31 for(i = 0; str[i]; i++) 32 printf("%X",str[i]); 33 printf("\n"); 34 } 35 return 0; 36 }
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标签：style blog http color java os io for
原文地址：http://www.cnblogs.com/crackpotisback/p/3886660.html
