public static IList <IList <int> > ThreeSum(int[] nums)
{
if (nums.Length == 0)
{
return(new List <IList <int> >());
}
Dictionary <int, int> num_count = new Dictionary <int, int>();
//build dictionary
foreach (int n in nums)
{
if (num_count.ContainsKey(n))
{
num_count[n]++;
}
else
{
num_count.Add(n, 1);
}
}
Array.Sort(nums);
int seekVal;
int counter = 0;
Dictionary <String, threeTuple> result = new Dictionary <string, threeTuple>();
threeTuple buff;
// give each 2x2 triangle combination
for (int i = 0; i < nums.Length; i++)
{
for (int j = nums.Length - 1; j > i; j--)
{
seekVal = -(nums[j] + nums[i]);
Console.WriteLine("i:" + i + "|j:" + j);
Console.WriteLine("Num i:" + nums[i] + "|Num j:" + nums[j] + "|seek:" + seekVal);
if (seekVal < nums[i])
{
continue;
}
/* if seek value is out of the array's range
* TEST FOR MORE OPTIMIZATION
*/
if (nums[nums.Length - 1] < seekVal)
{
j = i;
} //sortedNums[0] > seekVal ||
if (num_count.ContainsKey(seekVal))
{
counter = num_count[seekVal];
if (nums[i] == seekVal)
{
counter--;
}
if (nums[j] == seekVal)
{
counter--;
}
if (counter < 1)
{
continue;
}
buff = new threeTuple(nums[i], nums[j], seekVal);
if (!result.ContainsKey(buff.ToString()))
{
result.Add(buff.ToString(), buff);
}
}
}
}
IList <IList <int> > fOut = new List <IList <int> >();
foreach (threeTuple t in result.Values)
{
fOut.Add(t.toList());
}
return(fOut);
}
public static IList <IList <int> > ThreeSum_2(int[] nums)
{
//
if (nums.Length == 0)
{
return(new List <IList <int> >());
}
Dictionary <int, int> num_count = new Dictionary <int, int>();
//build dictionary
foreach (int n in nums)
{
if (num_count.ContainsKey(n))
{
num_count[n]++;
}
else
{
num_count.Add(n, 1);
}
}
int[] sortedNums = new int[num_count.Keys.Count];
num_count.Keys.CopyTo(sortedNums, 0);
Array.Sort(sortedNums);
int seekVal;
Dictionary <String, threeTuple> result = new Dictionary <string, threeTuple>();
threeTuple buff;
// give each 2x2 triangle combination
for (int i = 0; i < sortedNums.Length; i++)
{
for (int j = sortedNums.Length - 1; j > i; j--)
{
seekVal = -(sortedNums[j] + sortedNums[i]);
Console.WriteLine("i:" + i + "|j:" + j);
Console.WriteLine("Num i:" + sortedNums[i] + "|Num j:" + sortedNums[j] + "|seek:" + seekVal);
/* if seek value is out of the array's range
* TEST FOR MORE OPTIMIZATION
*/
if (sortedNums[sortedNums.Length - 1] < seekVal)
{
j = i; //sortedNums[0] > seekVal ||
}
// if seek value is a duplciate. will be saved for straight pass of sortedNums
if (seekVal == sortedNums[i] || seekVal == sortedNums[j])
{
continue;
}
if (num_count.ContainsKey(seekVal))
{
buff = new threeTuple(sortedNums[i], sortedNums[j], seekVal);
if (!result.ContainsKey(buff.ToString()))
{
result.Add(buff.ToString(), buff);
}
}
}
}
foreach (int i in sortedNums)
{
if (num_count[i] < 2)
{
continue;
}
seekVal = -2 * i;
num_count[i] -= 2;
if (num_count.ContainsKey(seekVal) && num_count[seekVal] > 0)
{
buff = new threeTuple(i, i, seekVal);
if (!result.ContainsKey(buff.ToString()))
{
result.Add(buff.ToString(), buff);
}
}
num_count[i] += 2;
}
IList <IList <int> > fOut = new List <IList <int> >();
foreach (threeTuple t in result.Values)
{
fOut.Add(t.toList());
}
return(fOut);
}
