Update #306 Additive Number.java

Author: zhmuch

#306 Additive Number.java

@@ -1,6 +1,5 @@
 //  Some bugs;
 
-
 import java.util.*;
 
 public class Solution {
@@ -15,48 +14,73 @@ public boolean isAdditiveNumber(String num) {
         this.num = num;
         int max = Math.min(num.length() / 2, 9);
 
-        for(int i = 0; i < max; i++)
-            for(int j = 0; j < max; j++){
-                int prepre = Integer.parseInt(num.substring(0, i + 1));
-                int pre = Integer.parseInt(num.substring(i + 1, i + j + 2));
-                if(dfs(prepre, pre, Math.max(i, j) + 1, i + j + 2))
+//        System.out.println("max: " + max);
+
+        if(num.charAt(0) == '0'){
+            if(num.charAt(1) == '0'){
+                if(dfs(0, 0, 1, 2))
                     return true;
             }
+            else
+                for(int j = 0; j < max; j++){
+                    int prepre = 0;
+                    int pre = Integer.parseInt(num.substring(1, j + 2));
+                    if(dfs(prepre, pre, j + 1, j + 2))
+                        return true;
+                }
+        } else {
+            for(int i = 0; i < max; i++){
+                if(num.charAt(i + 1) == '0'){
+                    if(dfs(Integer.parseInt(num.substring(0, i + 1)), 0, i + 1, i + 2))
+                        return true;
+                }
+                else
+                    for(int j = 0; i + j < max && j < max; j++){
+                        int prepre = Integer.parseInt(num.substring(0, i + 1));
+                        int pre = Integer.parseInt(num.substring(i + 1, i + j + 2));
+                        if(dfs(prepre, pre, Math.max(i, j) + 1, i + j + 2))
+                            return true;
+                    }
+            }
+        }
+
 
         return false;
     }
 
     private boolean dfs(int prepre, int pre, int digits, int idx) {
-        
-        // System.out.println(prepre + "  " + pre + "  " + digits + "  " + idx);
-        
+
+//        System.out.println("prepre: " + prepre + "  pre: " + pre + "  digits: " + digits + "  idx: " + idx);
+
         if(idx >= num.length())
             return true;
-        
+
         if(num.charAt(idx) == '0' && digits > 1)
             return false;
 
         if(num.length() - idx < digits)
             return false;
-        
+
         boolean res = false;
-        
+
         //  digits
         int pos = Integer.parseInt(num.substring(idx, idx + digits));
-        if(pos == prepre + pre)
+        if(pos == prepre + pre){
             res = dfs(pre, pos, digits, idx + digits);
-        
+        }
+
         if(res)
-            return res;
-        
+            return true;
+
         //  digits + 1;
-        if(idx + digits + 1 <= num.length() && digits < 9){
+        if(num.charAt(idx) != '0' && idx + digits + 1 <= num.length() && digits < 9){
             int poss = Integer.parseInt(num.substring(idx, idx + digits + 1));
-            if(poss == prepre + pre)
+            if(poss == prepre + pre){
                 res = dfs(pre, poss, digits + 1, idx + digits + 1);
+            }
         }
-        
-        
+
+
         return res;
     }
 }