refactor 282

fishercoder1534 · fishercoder1534 · commit 00706a33e4dd · 2018-11-25T07:49:44.000-08:00
diff --git a/src/main/java/com/fishercoder/solutions/_282.java b/src/main/java/com/fishercoder/solutions/_282.java
@@ -4,7 +4,11 @@
 import java.util.List;
 
 /**
- * Given a string that contains only digits 0-9 and a target value, return all possibilities to add binary operators (not unary) +, -, or * between the digits so they evaluate to the target value.
+ * 282. Expression Add Operators
+ *
+ * Given a string that contains only digits 0-9 and a target value,
+ * return all possibilities to add binary operators (not unary) +, -, or * between the digits
+ * so they evaluate to the target value.
 
  Examples:
  "123", 6 -> ["1+2+3", "1*2*3"]
@@ -15,39 +19,41 @@
  */
 public class _282 {
 
-    public List<String> addOperators(String num, int target) {
-        List<String> res = new ArrayList<String>();
-        StringBuilder sb = new StringBuilder();
-        dfs(res, sb, num, 0, target, 0, 0);
-        return res;
+    public static class Solution1 {
+        public List<String> addOperators(String num, int target) {
+            List<String> res = new ArrayList<String>();
+            StringBuilder sb = new StringBuilder();
+            dfs(res, sb, num, 0, target, 0, 0);
+            return res;
 
-    }
-
-    private void dfs(List<String> res, StringBuilder sb, String num, int pos, int target, long prev, long multi) {
-        if (pos == num.length()) {
-            if (target == prev) {
-                res.add(sb.toString());
-            }
-            return;
         }
-        for (int i = pos; i < num.length(); i++) {
-            if (num.charAt(pos) == '0' && i != pos) {
-                break;
+
+        private void dfs(List<String> res, StringBuilder sb, String num, int pos, int target, long prev, long multi) {
+            if (pos == num.length()) {
+                if (target == prev) {
+                    res.add(sb.toString());
+                }
+                return;
             }
-            long curr = Long.parseLong(num.substring(pos, i + 1));
-            int len = sb.length();
-            if (pos == 0) {
-                dfs(res, sb.append(curr), num, i + 1, target, curr, curr);
-                sb.setLength(len);
-            } else {
-                dfs(res, sb.append("+").append(curr), num, i + 1, target, prev + curr, curr);
-                sb.setLength(len);
-
-                dfs(res, sb.append("-").append(curr), num, i + 1, target, prev - curr, -curr);
-                sb.setLength(len);
-
-                dfs(res, sb.append("*").append(curr), num, i + 1, target, prev - multi + multi * curr, multi * curr);
-                sb.setLength(len);
+            for (int i = pos; i < num.length(); i++) {
+                if (num.charAt(pos) == '0' && i != pos) {
+                    break;
+                }
+                long curr = Long.parseLong(num.substring(pos, i + 1));
+                int len = sb.length();
+                if (pos == 0) {
+                    dfs(res, sb.append(curr), num, i + 1, target, curr, curr);
+                    sb.setLength(len);
+                } else {
+                    dfs(res, sb.append("+").append(curr), num, i + 1, target, prev + curr, curr);
+                    sb.setLength(len);
+
+                    dfs(res, sb.append("-").append(curr), num, i + 1, target, prev - curr, -curr);
+                    sb.setLength(len);
+
+                    dfs(res, sb.append("*").append(curr), num, i + 1, target, prev - multi + multi * curr, multi * curr);
+                    sb.setLength(len);
+                }
             }
         }
     }
