# 13.11.2025 [3228. Maximum Number of Operations to Move Ones to the End]
Max steps to move all ones to the right #medium
13.11.2025
3228. Maximum Number of Operations to Move Ones to the End medium blog post substack youtube
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Problem TLDR
Max steps to move all ones to the right #medium
Intuition
// 1010101010
// 1010101001
// 1010100011
// 1010000111
// 1000001111
// 0000011111
//
// a b c d e
// 1010101010
// 0110101010 a-1
// 0101101010 b-1
// 0011101010 b-2
// 0011011010 c-1
// 0010111010 c-2
// 0001111010 c-3
// 0001110110 d-1
// 0001101110 d-2
// 0001011110 d-3
// 0000111110 d-5
// 0000111110 e-5 bubble ‘0’ to the left
// go from left to right, each zero gives +(number of ones)
// dedup zeros
Go from left to right and count ones; each zero adds +count_ones
Approach
skip duplicate consequent zeros
Complexity
Time complexity: $$O(n)$$
Space complexity: $$O(1)$$
Code
// 39ms
fun maxOperations(s: String) = s.indices.fold(0 to 0) {(o,r),i->
o+(s[i]-’0’) to if (s[i]>’0’||i>0 && s[i]==s[i-1]) r else r+o}.second
// 0ms
pub fn max_operations(s: String) -> i32 {
let (mut o, s) = (0, s.as_bytes());
(0..s.len()).map(|i| { o += (s[i] - b’0’) as i32;
if i>0&&s[i]==s[i-1]||s[i]==b’1’{0}else{o}
}).sum()
}