B. Binary Number
http://codeforces.com/problemset/problem/92/B
time limit per test
memory limit per test
input
output
Little walrus Fangy loves math very much. That's why when he is bored he plays with a number performing some operations.
x and wants to get a number one from it. While x is not equal to 1, Fangy repeats the following action: if x is odd, then he adds 1 to it, otherwise he divides x by 2. Fangy knows that for any positive integer number the process ends in finite time.
x?
Input
x in a binary system. It is guaranteed that the first digit of x is different from a zero and the number of its digits does not exceed 106.
Output
Print the required number of actions.
Sample test(s)
input
1
output
0
input
1001001
output
12
input
101110
output
8
Note
101110 is even, which means that we should divide it by 2. After the dividing Fangy gets an odd number 10111 and adds one to it. Number 11000 can be divided by 2 three times in a row and get number 11. All that's left is to increase the number by one (we get 100), and then divide it by 2 two times in a row. As a result, we get 1.
简单贪心，怎么处理n详见代码。
完整代码：
/*30ms,1000KB*/
#include<cstdio>
#include<cstring>
char num[1000001];
int main()
{
scanf("%s", num);
int len = strlen(num) - 1, count = 0;
while (len)
{
if (num[len] == '0')
{
++count;
for (; num[--len] == '0'; ++count)
;
}
else
{
count += 2;
for (; --len && num[len] == '1'; ++count)
;
if (len)
num[len] = '1';
else///连续读1读到最开头的情况，+1
++count;
}
}
printf("%d", count);
return 0;
}
