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3 | 3 | https://github.com/jackzhenguo/LeetCodeManager |
4 | 4 |
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5 | 5 | ## Bit Mainpulation |
6 | | -* [CSDN:#476 Number Complement](http://blog.csdn.net/daigualu/article/details/72843822) |
7 | | - > get bits for a number</br> |
| 6 | +* [CSDN:#397 Integer Replacement](http://blog.csdn.net/daigualu/article/details/72861851) |
| 7 | + > Following coding refers to A couple of Java solutions with explanations |
| 8 | + > But it has a bug of overflowing and I fix it.</br> |
8 | 9 | ```C# |
9 | | - public int FindComplement(int num) |
10 | | - { |
11 | | - int bits = 1; //num including bits |
12 | | - while (Math.Pow(2, bits) <= num) |
13 | | - bits++; |
14 | | - int sum = (int) Math.Pow(2, bits) - 1;//sum =Pow(2,n)-1: sum of n bits 1 |
15 | | - return sum - num; //sum - num is the complement |
16 | | - |
| 10 | + public int IntegerReplacement(int n) { |
| 11 | + int cnt = 0; |
| 12 | + long bign = (long)n; //n = Int32.MaxValue(2147483647),adds 1 and would overflow |
| 13 | + while (bign != 1) { |
| 14 | + if ((bign & 1) == 0) { //even number |
| 15 | + bign >>= 1; |
| 16 | + } |
| 17 | + //It is enough to examine the last two digits to figure out |
| 18 | + //whether incrementing or decrementing will give more 1's. Indeed, |
| 19 | + //if a number ends with 01, |
| 20 | + //then certainly decrementing is the way to go. Otherwise, if it ends with 11, |
| 21 | + //then certainly incrementing is at least as good as decrementing (*011 -> *010 / *100) or |
| 22 | + // even better (if there are three or more 1's). |
| 23 | + else if (bign == 3|| ((bign >> 1) & 1) == 0) { //*01 |
| 24 | + --bign; |
| 25 | + } |
| 26 | + else { //*11 |
| 27 | + ++bign; |
17 | 28 | } |
| 29 | + ++cnt; |
| 30 | + } |
| 31 | + return cnt; |
| 32 | + } |
18 | 33 | ``` |
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