A string of '0's and '1's is monotone increasing if it consists of some number of '0's (possibly 0), followed by some number of '1's (also possibly 0.)
We are given a string S of '0's and '1's, and we may flip any '0' to a '1' or a '1' to a '0'.
Return the minimum number of flips to make S monotone increasing.
Example 1:
Input: "00110" Output: 1 Explanation: We flip the last digit to get 00111.
Example 2:
Input: "010110" Output: 2 Explanation: We flip to get 011111, or alternatively 000111.
Example 3:
Input: "00011000" Output: 2 Explanation: We flip to get 00000000.
Note:
1 <= S.length <= 20000S only consists of '0' and '1' characters.struct Solution;
impl Solution {
fn min_flips_mono_incr(s: String) -> i32 {
let n = s.len();
let s: Vec<char> = s.chars().collect();
let mut left = vec![0; n];
let mut ones = 0;
let mut right = vec![0; n];
let mut zeros = 0;
for i in 0..n {
left[i] = ones;
if s[i] == '1' {
ones += 1;
}
}
for i in (0..n).rev() {
right[i] = zeros;
if s[i] == '0' {
zeros += 1;
}
}
let mut res = std::i32::MAX;
for i in 0..n {
res = res.min(left[i] + right[i]);
}
res
}
}
#[test]
fn test() {
let s = "00110".to_string();
let res = 1;
assert_eq!(Solution::min_flips_mono_incr(s), res);
let s = "010110".to_string();
let res = 2;
assert_eq!(Solution::min_flips_mono_incr(s), res);
let s = "00011000".to_string();
let res = 2;
assert_eq!(Solution::min_flips_mono_incr(s), res);
}