1 public class MergeSort { 2      3     public static void sort(int [] A,int p, int r) 4     {    5         if(p<r) 6         { 7             int q = (int) Math.floor( (p+r)/2 ); 8             sort(A,p,q); 9             sort(A,q+1,r);10             merge(A,p,q,r);11         }12         return ;13 14     }15     public static void merge(int [] A, int p, int q, int r)16     {17         int n1 = q-p+1;18         int n2 = r-q;19         int [] L = new int[n1];20         int [] R = new int[n2];21         for(int i=0; i<n1; i++)22           L[i] = A[p+i];23         for(int i=0; i<n2;i++)24             R[i]=A[q+i+1];25         26         int i=0;27         int j=0;28         int counter = p;29         while(i<L.length && j<R.length)30         {31             if(L[i]<=R[j])32             {33                 A[counter]=L[i];34                 i++;35             }36             else37             {38                 A[counter]=R[j];39                 j++;40             }41             counter++;42         }43         if(i==L.length)44         {45             for(int k=j;k<R.length;k++)46                 A[counter++] = R[k];47         }48         else49         {50             for(int k=i;k<L.length;k++)51                 A[counter++] = L[k];52         }    53     }54 }

 1 public class SumTwoEqual { 2  3     /** 4      * @param args 5      */ 6     public static boolean TestExists(int A[],int X) 7     { 8         MergeSort.sort(A, 0, A.length - 1 ); 9         int i = 0;10         int j = A.length-1;11         while(i<j)12         {13             if(A[i]+A[j]==X)14                 return true;15             else if(A[i]+A[j] > X)16                 j--;17             else 18                 i++;19         }20         return false;21     }22 23     public static void main(String[] args) {24         int A[] = {1,2,5,7,9,14,25,35,13,15};25         boolean a = TestExists(A,22);26         System.out.println(a);27     }28 }