topic:
Given a 32-bit signed integer, invert the numbers in the integer.
Example 1:
Input: 123 Output: 321
Example 2:
Input: -123 output: -321
Example 3:
Input: 120 Output: 21
Notice:
Suppose our environment can only store 32-bit signed integers whose values are in the range [−231, 231 − 1]. According to this assumption, if the inverted integer overflows, 0 is returned.
A possible answer (java implementation):
public class Id07ReverseInteger { public int reverse(int x) { String xString = String.valueOf(x); char[] intChars = xString.toCharArray(); boolean negative = false; int size = intChars.length; if (intChars[0] == '-') { negative = true; size -= 1; } int forsize; if (size % 2 == 1) { forsize = (size - 1) / 2; } else { forsize = size / 2; } for (int i = 0; i < forsize; i++) { if (negative) { char temp = intChars[i + 1]; intChars[i + 1] = intChars[size - i]; intChars[size - i] = temp; } else { char temp = intChars[i]; intChars[i] = intChars[size - i - 1]; intChars[size - i - 1] = temp; } } try { //// TODO: 2018/4/28 Optimize maximum value judgment Integer result = Integer.valueOf( new String(intChars)); return result; } catch (NumberFormatException e) { return 0; } } public static void main(String[] args) { Id07ReverseInteger id07ReverseInteger = new Id07ReverseInteger(); id07ReverseInteger.reverse(Integer.MIN_VALUE); // System.out.println(Integer.valueOf("-0010")); } }