## 955. Delete Columns to Make Sorted II

You are given an array of `n`

strings `strs`

, all of the same length.

We may choose any deletion indices, and we delete all the characters in those indices for each string.

For example, if we have `strs = ["abcdef","uvwxyz"]`

and deletion indices `{0, 2, 3}`

, then the final array after deletions is `["bef", "vyz"]`

.

Suppose we chose a set of deletion indices `answer`

such that after deletions, the final array has its elements in **lexicographic** order (i.e., `strs[0] <= strs[1] <= strs[2] <= ... <= strs[n - 1]`

). Return *the minimum possible value of* `answer.length`

.

**Example 1:**

Input:strs = ["ca","bb","ac"]Output:1Explanation:After deleting the first column, strs = ["a", "b", "c"]. Now strs is in lexicographic order (ie. strs[0] <= strs[1] <= strs[2]). We require at least 1 deletion since initially strs was not in lexicographic order, so the answer is 1.

**Example 2:**

Input:strs = ["xc","yb","za"]Output:0Explanation:strs is already in lexicographic order, so we do not need to delete anything. Note that the rows of strs are not necessarily in lexicographic order: i.e., it is NOT necessarily true that (strs[0][0] <= strs[0][1] <= ...)

**Example 3:**

Input:strs = ["zyx","wvu","tsr"]Output:3Explanation:We have to delete every column.

**Constraints:**

`n == strs.length`

`1 <= n <= 100`

`1 <= strs[i].length <= 100`

`strs[i]`

consists of lowercase English letters.

## Rust Solution

```
struct Solution;
impl Solution {
fn min_deletion_size(a: Vec<String>) -> i32 {
let n = a.len();
let mut sorted = vec!["".to_string(); n];
let a: Vec<Vec<char>> = a.into_iter().map(|s| s.chars().collect()).collect();
let m = a[0].len();
for j in 0..m {
for i in 0..n {
sorted[i].push(a[i][j]);
}
if sorted.windows(2).any(|w| w[0] > w[1]) {
for i in 0..n {
sorted[i].pop();
}
}
}
(m - sorted[0].len()) as i32
}
}
#[test]
fn test() {
let a = vec_string!["ca", "bb", "ac"];
let res = 1;
assert_eq!(Solution::min_deletion_size(a), res);
let a = vec_string!["xc", "yb", "za"];
let res = 0;
assert_eq!(Solution::min_deletion_size(a), res);
let a = vec_string!["zyx", "wvu", "tsr"];
let res = 3;
assert_eq!(Solution::min_deletion_size(a), res);
}
```

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