20241218 finished.

src/problem/mod.rs

@@ -376,3 +376,5 @@ mod p1338_reduce_array_size_to_the_half;
 mod p1847_closest_room;
 
 mod p3291_minimum_number_of_valid_strings_to_form_target_i;
+
+mod p3292_minimum_number_of_valid_strings_to_form_target_ii;

src/problem/p3292_minimum_number_of_valid_strings_to_form_target_ii.rs

@@ -0,0 +1,90 @@
+/**
+ * [3292] Minimum Number of Valid Strings to Form Target II
+ */
+pub struct Solution {}
+
+// submission codes start here
+
+impl Solution {
+    pub fn min_valid_strings(words: Vec<String>, target: String) -> i32 {
+        let words: Vec<Vec<char>> = words.into_iter().map(|x| x.chars().collect()).collect();
+        let target: Vec<char> = target.chars().collect();
+
+        let calculate_prefix = |word: &Vec<char>, target: &Vec<char>| {
+            let s: Vec<char> = word
+                .iter()
+                .chain(['#'].iter())
+                .chain(target.iter())
+                .map(|x| x.clone())
+                .collect();
+            let mut result = vec![0; s.len()];
+
+            // KMP to calculate prefix array
+            for i in 1..s.len() {
+                let mut j = result[i - 1];
+                while j > 0 && s[i] != s[j] {
+                    j = result[j - 1];
+                }
+
+                if s[i] == s[j] {
+                    j += 1;
+                }
+                result[i] = j;
+            }
+
+            result
+        };
+
+        let n = target.len();
+        let mut back = vec![0; n];
+        for word in words.iter() {
+            let pi = calculate_prefix(word, &target);
+            let m = word.len();
+
+            for i in 0..n {
+                back[i] = back[i].max(pi[m + 1 + i]);
+            }
+        }
+
+        let mut dp = vec![0; n + 1];
+
+        for i in 1..=n {
+            dp[i] = 1e9 as i32;
+        }
+
+        for i in 0..n {
+            dp[i + 1] = dp[i + 1 - back[i]] + 1;
+            if dp[i + 1] > n as i32 {
+                return -1;
+            }
+        }
+
+        dp[n]
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_3292() {
+        assert_eq!(
+            3,
+            Solution::min_valid_strings(
+                vec_string!("abc", "aaaaa", "bcdef"),
+                "aabcdabc".to_owned()
+            )
+        );
+        assert_eq!(
+            2,
+            Solution::min_valid_strings(vec_string!("abababab", "ab"), "ababaababa".to_owned())
+        );
+        assert_eq!(
+            -1,
+            Solution::min_valid_strings(vec_string!("abcdef"), "xyz".to_owned())
+        );
+    }
+}