diff --git a/pom.xml b/pom.xml
index 9a832bd..584c394 100644
--- a/pom.xml
+++ b/pom.xml
@@ -68,11 +68,5 @@
             <version>RELEASE</version>
             <scope>compile</scope>
         </dependency>
-        <dependency>
-            <groupId>com.alibaba</groupId>
-            <artifactId>fastjson</artifactId>
-            <version>1.2.29</version>
-        </dependency>
-
     </dependencies>
 </project>
\ No newline at end of file
diff --git a/src/main/java/com/usc/Test.java b/src/main/java/com/usc/Test.java
index 4a11463..5fef7a4 100644
--- a/src/main/java/com/usc/Test.java
+++ b/src/main/java/com/usc/Test.java
@@ -1,34 +1,61 @@
 package com.usc;
 
-class Test {
-    public int firstBadVersion(int n) {
-        int l = 1, r = n;
-        while (l <= r) {
-            int mid = l + r >> 1;
-            // 1, 2, 3, 4, 5
-            // 0  0  0  1  1
-            boolean isBadMid = isBadVersion(mid);
-            if (mid -1 >= l && isBadMid && isBadVersion(mid-1) == false){
-                return mid;
+class Solution {
+    public int romanToInt(String s) {
+        int result = 0;
+        char numC;
+        for(int index = s.length() - 1 ; index != -1 ; index -- ){
+            numC = s.charAt(index);
+            if(numC == 'I'){
+                result += 1;
             }
-
-            // 版本错误
-            if (isBadMid) {
-                r = mid;
-            }else{
-                l = mid;
+            if(numC == 'V'){
+                result += 5;
+                if(index != 0 && s.charAt(index - 1) == 'I'){
+                    result --;
+                    index --;
+                }
+            }
+            if(numC == 'X'){
+                result += 10;
+                if(index != 0 && s.charAt(index - 1) == 'I'){
+                    result --;
+                    index --;
+                }
+            }
+            if(numC == 'L'){
+                result += 50;
+                if(index != 0 && s.charAt(index - 1) == 'X'){
+                    result -= 10;
+                    index --;
+                }
+            }
+            if(numC == 'C'){
+                result += 100;
+                if(index != 0 && s.charAt(index - 1) == 'X'){
+                    result -= 10;
+                    index --;
+                }
+            }
+            if(numC == 'D'){
+                result += 500;
+                if(index != 0 && s.charAt(index - 1) == 'C'){
+                    result -= 100;
+                    index --;
+                }
+            }
+            if(numC == 'M'){
+                result += 1000;
+                if(index != 0 && s.charAt(index - 1) == 'C'){
+                    result -= 100;
+                    index --;
+                }
             }
         }
-
-        return -1;
+        return result;
     }
 
-    public boolean isBadVersion(int n) {
-        if (n == 3) return true;
-        return false;
-    }
     public static void main(String[] args) {
-
-        new Test().firstBadVersion(3);
+        new Solution().romanToInt("IV");
     }
 }
\ No newline at end of file
diff --git a/src/main/java/com/usc/leetcode/DigitCounts.java b/src/main/java/com/usc/leetcode/DigitCounts.java
new file mode 100644
index 0000000..58cb4fe
--- /dev/null
+++ b/src/main/java/com/usc/leetcode/DigitCounts.java
@@ -0,0 +1,24 @@
+package com.usc.leetcode;
+
+/**
+ * 统计数字
+ */
+public class DigitCounts {
+    public static void main(String[] args) {
+        new DigitCounts().digitCounts(1, 12);
+    }
+
+    public int digitCounts(int k, int n) {
+        int ans = 0;
+        for(int i=0; i<=n; i++){
+            int j = i;
+            while(j > 0){
+                if (j % 10 == k) ans++;
+                j /= 10;
+            }
+        }
+
+
+        return ans;
+    }
+}
diff --git a/src/main/java/com/usc/leetcode/FindContentChildern.java b/src/main/java/com/usc/leetcode/FindContentChildern.java
index 6e4a731..e69de29 100644
--- a/src/main/java/com/usc/leetcode/FindContentChildern.java
+++ b/src/main/java/com/usc/leetcode/FindContentChildern.java
@@ -1,30 +0,0 @@
-package com.usc.leetcode;
-
-import java.util.Arrays;
-
-/**
- * @author jianjianduan
- * @date 2020/8/31 11:30 下午
- */
-public class FindContentChildern {
-    public static void main(String[] args) {
-        findContentChildren(new int[]{10, 9, 8, 7}, new int[]{5, 6, 7, 8});
-    }
-    public static int findContentChildren(int[] g, int[] s) {
-        Arrays.sort(g);
-        Arrays.sort(s);
-        int ans = 0;
-        int k = 0;
-        for(int i=0; i<g.length; i++){
-            for(int j=0; j<s.length; j++){
-                if (s[j] >= g[i]) {
-                    ans++;
-                    k++;
-                }
-                break;
-            }
-        }
-
-        return ans;
-    }
-}
diff --git a/src/main/java/com/usc/leetcode/RotateRight.java b/src/main/java/com/usc/leetcode/RotateRight.java
new file mode 100644
index 0000000..e69de29