Given a 32-bit signed integer, reverse digits of an integer.
Example 1:
Input: 123 Output: 321
Example 2:
Input: -123 Output: -321
Example 3:
Input: 120 Output: 21
Note:
Assume we are dealing with an environment which could only store integers within the 32-bit signed integer range: [−231, 231 − 1]. For the purpose of this problem, assume that your function returns 0 when the reversed integer overflows.
Solution 1 in C++
#include <iostream> #include <math.h> using namespace std; class Solution { public: int reverse(int x) { int y=x; long ret=0; long valid_range = pow(2,31); while(y) { ret *= 10; ret += (y %10); cout << ret << " - " << y << endl; y /= 10; } if ((ret<valid_range*(-1)) || (ret>(valid_range-1))) return 0; return ret; } }; int main(void) { Solution s; int testcase; testcase = 123; cout << testcase << " -> " << s.reverse(testcase) << endl; testcase = -123; cout << testcase << " -> " << s.reverse(testcase) << endl; testcase = 120; cout << testcase << " -> " << s.reverse(testcase) << endl; testcase = 1534236469; cout << testcase << " -> " << s.reverse(testcase) << endl; return 0; }
Solution 2 in C++
class Solution { public: int reverse(int x) { int rev = 0; while (x != 0) { int pop = x % 10; x /= 10; if (rev > INT_MAX/10 || (rev == INT_MAX / 10 && pop > 7)) return 0; if (rev < INT_MIN/10 || (rev == INT_MIN / 10 && pop < -8)) return 0; rev = rev * 10 + pop; } return rev; } };
Solution 3 in Java
class Solution { public int reverse(int x) { int rev = 0; while (x != 0) { int pop = x % 10; x /= 10; if (rev > Integer.MAX_VALUE/10 || (rev == Integer.MAX_VALUE / 10 && pop > 7)) return 0; if (rev < Integer.MIN_VALUE/10 || (rev == Integer.MIN_VALUE / 10 && pop < -8)) return 0; rev = rev * 10 + pop; } return rev; } }