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Copy path17. Letter Combinations of a Phone Number.java
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17. Letter Combinations of a Phone Number.java
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//BRUTE FORCE SOLUTION
class Solution {
public List<String> letterCombinations(String digits) {
int arr[] = new int[]{2,3,4,5,6,7,8,9};
String key[] = new String[]{"abc","def","ghi","jkl","mno","pqrs","tuv","wxyz"};
ArrayList<String> res = new ArrayList<String>();
int first = 0;
int second = 0;
int third = 0;
int fourth = 0;
if(digits.length()==0)
{
}
if(digits.length()==1)
{
int index =0;
first = Integer.parseInt(digits.charAt(0)+"");
for(int i=0;i<arr.length;i++)
{
if(arr[i]==first)
{
index = i;
break;
}
}
for(int i=0;i<key[index].length();i++)
{
res.add(key[index].charAt(i)+"");
}
}
else if(digits.length()==2)
{
first = Integer.parseInt(digits.charAt(0)+"");
second = Integer.parseInt(digits.charAt(1)+"");
int findex =0, sindex=0;
for(int i=0;i<arr.length;i++)
{
if(arr[i]==first)
{
findex = i;
}
if(arr[i]==second)
{
sindex = i;
}
}
//System.out.println(findex +" "+sindex);
for(int i=0;i<key[findex].length();i++)
{
for(int j=0;j<key[sindex].length();j++)
{
res.add(key[findex].charAt(i)+""+key[sindex].charAt(j)+"");
}
}
}
else if(digits.length()==3)
{
first = Integer.parseInt(digits.charAt(0)+"");
second = Integer.parseInt(digits.charAt(1)+"");
third = Integer.parseInt(digits.charAt(2)+"");
int findex =0, sindex=0, tindex =0;
for(int i=0;i<arr.length;i++)
{
if(arr[i]==first)
{
findex = i;
}
if(arr[i]==second)
{
sindex = i;
}
if(arr[i]==third)
{
tindex = i;
}
}
//System.out.println(findex +" "+sindex+" "+ tindex);
for(int i=0;i<key[findex].length();i++)
{
for(int j=0;j<key[sindex].length();j++)
{
for(int k=0;k<key[tindex].length();k++)
{
res.add(key[findex].charAt(i)+""+key[sindex].charAt(j)+""+key[tindex].charAt(k));
}
}
}
}
else if(digits.length()==4)
{
first = Integer.parseInt(digits.charAt(0)+"");
second = Integer.parseInt(digits.charAt(1)+"");
third = Integer.parseInt(digits.charAt(2)+"");
fourth = Integer.parseInt(digits.charAt(3)+"");
int findex =0, sindex=0, tindex =0, fourindex = 0;
for(int i=0;i<arr.length;i++)
{
if(arr[i]==first)
{
findex = i;
}
if(arr[i]==second)
{
sindex = i;
}
if(arr[i]==third)
{
tindex = i;
}
if(arr[i]==fourth)
{
fourindex = i;
}
}
System.out.println(first +" "+second+" "+ third+" "+ fourth);
System.out.println(findex +" "+sindex+" "+ tindex+" "+ fourindex);
for(int i=0;i<key[findex].length();i++)
{
for(int j=0;j<key[sindex].length();j++)
{
for(int k=0;k<key[tindex].length();k++)
{
for(int l=0;l<key[fourindex].length();l++)
{
res.add(key[findex].charAt(i)+""+key[sindex].charAt(j)+""+key[tindex].charAt(k)+""+key[fourindex].charAt(l));
}
}
}
}
}
return res;
}
}