diff --git a/src/problem/mod.rs b/src/problem/mod.rs
index 0d4e7c2..f2a0127 100644
--- a/src/problem/mod.rs
+++ b/src/problem/mod.rs
@@ -114,4 +114,5 @@ mod p68_text_justification;
 mod p125_valid_palindrome;
 mod p392_is_subsequence;
 mod p167_two_sum_ii_input_array_is_sorted;
-mod p209_minimum_size_subarray_sum;
\ No newline at end of file
+mod p209_minimum_size_subarray_sum;
+mod p30_substring_with_concatenation_of_all_words;
\ No newline at end of file
diff --git a/src/problem/p30_substring_with_concatenation_of_all_words.rs b/src/problem/p30_substring_with_concatenation_of_all_words.rs
new file mode 100644
index 0000000..7621a2a
--- /dev/null
+++ b/src/problem/p30_substring_with_concatenation_of_all_words.rs
@@ -0,0 +1,85 @@
+/**
+ * [30] Substring with Concatenation of All Words
+ */
+pub struct Solution {}
+
+// submission codes start here
+use std::collections::HashMap;
+
+impl Solution {
+    pub fn find_substring(s: String, words: Vec<String>) -> Vec<i32> {
+        let mut result = Vec::new();
+
+        let m = words.len();
+        let n = words[0].len();
+        let ls = s.len();
+
+        for start in 0..n {
+            if start + m * n > ls {
+                break;
+            }
+
+            let mut differ = HashMap::new();
+
+            for i in 0..m {
+                let word = s[start + i * n..start + i * n + n].to_owned();
+
+                let entry = differ.entry(word).or_insert(0);
+                *entry += 1;
+            }
+
+            for word in (&words).to_owned() {
+                let entry = differ.entry(word.clone()).or_insert(0);
+                *entry -= 1;
+
+                if *entry == 0 {
+                    differ.remove(&word);
+                }
+            }
+
+            // 滑动窗口开始滑动
+            for i in (start..ls - m * n + 1).step_by(n) {
+                if i != start {
+                    // 新加入的word
+                    let end_word = s[i + (m - 1) * n..i + m * n].to_owned();
+                    let entry = differ.entry(end_word.clone()).or_insert(0);
+                    *entry += 1;
+
+                    if *entry == 0 {
+                        differ.remove(&end_word);
+                    }
+
+                    // 滑动后被移除的word
+                    let begin_word = s[i - n..i].to_owned();
+                    let entry = differ.entry(begin_word.clone()).or_insert(0);
+                    *entry -= 1;
+
+                    if *entry == 0 {
+                        differ.remove(&begin_word);
+                    }
+                }
+
+                if differ.len() == 0 {
+                    result.push(i as i32);
+                }
+            }
+        }
+
+        result
+    }
+}
+
+// submission codes end
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_30() {
+        assert_eq!(vec![0,9], Solution::find_substring("barfoothefoobarman".to_owned(), vec![
+            "foo".to_owned(),
+            "bar".to_owned()
+        ]))
+    }
+}