LeetCode Entry
1945. Sum of Digits of String After Convert
Sum of number chars k times
1945. Sum of Digits of String After Convert easy
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Problem TLDR
Sum of number chars k times #easy #simulation
Intuition
- the first transformation is different:
c - 'a' + 1 - other transformations:
c - '0'
Approach
- we can do it with strings or with just numbers
Complexity
-
Time complexity: \(O(n)\)
-
Space complexity: \(O(1)\)
Code
fun getLucky(s: String, k: Int) = (1..<k).fold(
s.map { "${it - 'a' + 1}" }.joinToString("").sumOf { it - '0' }
) { r, t -> r.toString().sumOf { it.code - '0'.code }}
pub fn get_lucky(s: String, k: i32) -> i32 {
let dig = |x| { let (mut s, mut x) = (0, x);
while x > 0 { s += x % 10; x /= 10 }; s};
(1..k).fold(s.bytes().map(|b|
dig(b as i32 - 96)).sum(), |r, t| dig(r))
}
int getLucky(string s, int k) {
auto dig = [](int x) {
int s = 0;
while (x > 0) { s += x % 10; x /= 10; }
return s;
};
int sum = 0;
for (char c : s) sum += dig(c - 'a' + 1);
while (k-- > 1) sum = dig(sum);
return sum;
}