Problem
You are given a positive integer n. Each digit of n has a sign according to the following rules:
The most significant digit is assigned a positive sign.
Each other digit has an opposite sign to its adjacent digits.
Return the sum of all digits with their corresponding sign.
Example 1:
Input: n = 521
Output: 4
Explanation: (+5) + (-2) + (+1) = 4.
Example 2:
Input: n = 111
Output: 1
Explanation: (+1) + (-1) + (+1) = 1.
Example 3:
Input: n = 886996
Output: 0
Explanation: (+8) + (-8) + (+6) + (-9) + (+9) + (-6) = 0.
Constraints:
1 <= n <= 109
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Solution (Java)
class Solution {
public int alternateDigitSum(int n) {
String s=Integer.toString(n);
// char ch[]=s.toCharArray();
int res=0,r1=0,r2=0;
for(int i=0;i<s.length();i++)
{
char c=s.charAt(i);
if(i%2==0)
{
r1=r1+(c-'0');
}
else if(i%2!=0)
{
r2=r2-(c-'0');
}
}
res=r1+r2;
return res;
}
}
Explain:
nope.
Complexity:
- Time complexity : O(n).
- Space complexity : O(n).