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zhangtemplarzhangtemplar
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Update RestoreIPAddresses.java
Submission Result: Compile Error Line 6: cannot find symbol: variable length Submission Result: Compile Error Line 24: cannot find symbol: constructor String(int) Input: "010010" Output: ["0.1.0.10","0.1.0.10","0.1.1.0","0.10.0.10","0.10.1.0","0.100.1.0","1.0.0.10","1.0.1.0","1.0.1.0","10.0.1.0"] Expected: ["0.10.0.10","0.100.1.0"] Submission Result: Compile Error Line 62: illegal start of expression Submission Result: Wrong Answer L 44 Input: "25525511135" Output: [] Expected: ["255.255.11.135","255.255.111.35"]
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‎src/Solution/RestoreIPAddresses.java‎

Lines changed: 63 additions & 105 deletions
Original file line numberDiff line numberDiff line change
@@ -1,126 +1,84 @@
1-
package Solution;
2-
3-
import java.util.ArrayList;
4-
5-
public class RestoreIPAddresses {
6-
7-
/**
8-
* @param args
9-
*/
10-
public static void main(String[] args) {
11-
// TODO Auto-generated method stub
12-
RestoreIPAddresses instance=new RestoreIPAddresses();
13-
System.out.println(instance.restoreIpAddresses("010010"));
14-
}
15-
16-
public ArrayList<String> restoreIpAddresses(String s) {
17-
// Start typing your Java solution below
18-
// DO NOT write main() function
19-
// we will use recursion, however, parse the string in triple
20-
ArrayList<String> result=new ArrayList<String>();
21-
// obviously illegal case
22-
if (s==null || s.length()<4 || s.length()>12)
1+
public class Solution {
2+
public ArrayList<String> restoreIpAddresses(String s) {
3+
// IMPORTANT: Please reset any member data you declared, as
4+
// the same Solution instance will be reused for each test case.
5+
// we will use backtrace
6+
if (s==null || s.length()<4)
237
{
24-
return result;
8+
return new ArrayList<String>();
259
}
26-
int[] cuts=new int[3];
27-
cuts[0]=1;
28-
result.addAll(restoreIpAddresses(s, cuts, 1));
29-
cuts[0]=2;
30-
result.addAll(restoreIpAddresses(s, cuts, 1));
31-
cuts[0]=3;
32-
result.addAll(restoreIpAddresses(s, cuts, 1));
33-
return result;
10+
return restoreIpAddresses(s, 0, new ArrayList<Integer>());
3411
}
3512

36-
// start indicates the string we are parsing
37-
// cuts for the current cutting position (the start of each segment)
38-
// n indicates the number of segements already obtained
39-
private ArrayList<String> restoreIpAddresses(String s, int[] cuts, int n)
13+
/**
14+
* @param start is the index of char we can use
15+
*/
16+
private ArrayList<String> restoreIpAddresses(String s, int start, ArrayList<Integer> base)
4017
{
4118
ArrayList<String> result=new ArrayList<String>();
42-
// we first check the string are good so far
43-
if (cuts[n-1]>=s.length())
44-
{
45-
return result;
46-
}
47-
// first we will check the previous section is valid or not
48-
long val;
49-
if (n==1)
19+
// we finish the string
20+
if (start>=s.length())
5021
{
51-
if (!validSegment(s, 0, cuts[0]))
22+
if (base.size()==4)
5223
{
53-
return result;
24+
StringBuffer str=new StringBuffer();
25+
str.append(base.get(0));
26+
str.append('.');
27+
str.append(base.get(1));
28+
str.append('.');
29+
str.append(base.get(2));
30+
str.append('.');
31+
str.append(base.get(3));
32+
result.add(str.toString());
5433
}
55-
val=Long.parseLong(s.substring(0, cuts[0]));
5634
}
57-
else
35+
// the string is not finished yet and the ip address is not complete yet
36+
// however, we need to avoid '00' of something similar
37+
else if(base.size()<4)
5838
{
59-
if (!validSegment(s, cuts[n-2], cuts[n-1]))
39+
ArrayList<Integer> entry=null;
40+
// we can have triple here
41+
// 1 the string is not long enough
42+
// 2 the string has value >255
43+
// 3 the string has something like 0xx
44+
if (start+2<s.length() && (s.charAt(start)-'0')*100+(s.charAt(start+1)-'0')*10+(s.charAt(start+2)-'0')<=255 && (s.charAt(start)-'0')*100+(s.charAt(start+1)-'0')*10+(s.charAt(start+2)-'0')>99)
6045
{
61-
return result;
46+
// add this single char
47+
entry=new ArrayList<Integer>(base);
48+
entry.add(s.charAt(start)-'0');
49+
result.addAll(restoreIpAddresses(s, start+1, entry));
50+
// also check the two char
51+
entry=new ArrayList<Integer>(base);
52+
entry.add((s.charAt(start)-'0')*10+(s.charAt(start+1)-'0'));
53+
result.addAll(restoreIpAddresses(s, start+2, entry));
54+
// and triple
55+
entry=new ArrayList<Integer>(base);
56+
entry.add((s.charAt(start)-'0')*100+(s.charAt(start+1)-'0')*10+(s.charAt(start+2)-'0'));
57+
result.addAll(restoreIpAddresses(s, start+3, entry));
6258
}
63-
val=Long.parseLong(s.substring(cuts[n-2], cuts[n-1]));
64-
}
65-
// this is not a valid segment
66-
if (val>255 || val<0)
67-
{
68-
return result;
69-
}
70-
// everything is good so far
71-
if (n==3)
72-
{
73-
// we have finished the cutting, but need to check the last segment
74-
if (!validSegment(s, cuts[n-1], s.length()))
59+
// we can have double
60+
// 1 the string is not long enough
61+
// 2 the string is something like 0x
62+
else if(start+1<s.length() && (s.charAt(start)-'0')*10+(s.charAt(start+1)-'0')>9)
7563
{
76-
return result;
77-
}
78-
val=Integer.parseInt(s.substring(cuts[n-1], s.length()));
79-
if (val>255 || val<0)
80-
{
81-
return result;
64+
// add this single char
65+
entry=new ArrayList<Integer>(base);
66+
entry.add(s.charAt(start)-'0');
67+
result.addAll(restoreIpAddresses(s, start+1, entry));
68+
// also check the two char
69+
entry=new ArrayList<Integer>(base);
70+
entry.add((s.charAt(start)-'0')*10+(s.charAt(start+1)-'0'));
71+
result.addAll(restoreIpAddresses(s, start+2, entry));
8272
}
73+
// only single
8374
else
8475
{
85-
result.add(string2IP(s, cuts));
86-
return result;
76+
// add this single char
77+
entry=new ArrayList<Integer>(base);
78+
entry.add(s.charAt(start)-'0');
79+
result.addAll(restoreIpAddresses(s, start+1, entry));
8780
}
8881
}
89-
else
90-
{
91-
// just found the possible cutting location
92-
for (int i=cuts[n-1]+1; i<s.length(); i++)
93-
{
94-
cuts[n]=i;
95-
result.addAll(restoreIpAddresses(s, cuts, n+1));
96-
cuts[n]=0;
97-
}
98-
return result;
99-
}
100-
}
101-
102-
private boolean validSegment(String s, int start, int end)
103-
{
104-
if (start==end-1)
105-
{
106-
return true;
107-
}
108-
else
109-
{
110-
return s.charAt(start)!='0';
111-
}
112-
}
113-
114-
private String string2IP(String s, int[]cuts)
115-
{
116-
StringBuffer result=new StringBuffer();
117-
result.append(s.substring(0, cuts[0]));
118-
result.append('.');
119-
result.append(s.substring(cuts[0], cuts[1]));
120-
result.append('.');
121-
result.append(s.substring(cuts[1], cuts[2]));
122-
result.append('.');
123-
result.append(s.substring(cuts[2], s.length()));
124-
return result.toString();
82+
return result;
12583
}
12684
}

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