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7. Reverse Integer.cpp
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7. Reverse Integer.cpp
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/* Given a signed 32-bit integer x, return x with its digits reversed. If reversing x causes the value to go outside the signed 32-bit integer range [-231, 231 - 1], then return 0.
Assume the environment does not allow you to store 64-bit integers (signed or unsigned).
Example 1:
Input: x = 123
Output: 321
Example 2:
Input: x = -123
Output: -321
Example 3:
Input: x = 120
Output: 21
Constraints:
-231 <= x <= 231 - 1 */
//code
class Solution {
public:
// find out the reversed Number
//if it is out of the 32 bit range then return 0
int reverse(int x) {
// we know that The highest bit is often called the "sign bit" because if it's 0, the number is positive, and if it's 1, the value is negative (for signed values).
//so take a variable sign and initialize it with 1
int sign = 1;
if(x<0){
sign = -1 ;//if the number is negative we will make the sign value -1
x = -1ll * x;
}
long long reversedNum = 0;
while(x>0){
int rem = x%10; //finding the last digit
reversedNum = reversedNum*10 + rem;
x = x/10;
}
reversedNum = reversedNum * sign;
if(reversedNum <INT_MIN || reversedNum >INT_MAX)return 0;
return int(reversedNum);
}
};