TodayUpdate.md

Today Update

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Bit Mainpulation

• CSDN:#397 Integer Replacement

  Following coding refers to A couple of Java solutions with explanations But it has a bug of overflowing and I fix it.
  

   public int IntegerReplacement(int n) {
       int cnt = 0;
       long bign = (long)n; //n = Int32.MaxValue(2147483647),adds 1 and would overflow
       while (bign != 1) {
       if ((bign & 1) == 0) { //even number
           bign >>= 1;
         } 
         //It is enough to examine the last two digits to figure out 
         //whether incrementing or decrementing will give more 1's. Indeed, 
         //if a number ends with 01, 
         //then certainly decrementing is the way to go. Otherwise, if it ends with 11, 
         //then certainly incrementing is at least as good as decrementing (*011 -> *010 / *100) or
         // even better (if there are three or more 1's).
         else if (bign == 3|| ((bign >> 1) & 1) == 0) { //*01
           --bign;
         }
         else { //*11
           ++bign;
       }
       ++cnt;
      } 
      return cnt;
   }