Minimum difference between two sorted arrays

Problem solving with programming: Minimum difference between two sorted arrays
Given two arrays sorted in ascending order, find the absolute minimum difference between any pair of elements |a-b| such that a is from one array and b is from another array.

1. Take two indices i, j which point to the beginning of the two arrays (i.e 0)
2. Take variable MinDiff and assign it the maximum possible value
3. If array1[i] and array2[j] are equal return 0 
4. Otherwise update MinDiff if abs( array1[i] - array2[j] ) is the new minimum.
5. If array1[i] > array2[j] move second index(j) forward otherwise move first index (i) forward.
6. Repeat the above procedure until we reach the end of any of the two arrays.
7. Finally process the remaining part of left-over array to update MinDiff.

http://wxx5433.github.io/min-abs.html

You have two arrays of integers, where the integers do not repeat and the two arrays have no common integers.

Let x be any integer in the first array, y any integer in the second. Find min(Abs(x-y)). That is, find the smallest difference between any of the integers in the two arrays.

Assumptions: Assume both arrays are sorted in ascending order.

public static int minAbs(int[] a, int[] b) {
    if (a == null || b == null || a.length == 0 || b.length == 0) {
        return -1;
    }
    int i = 0, j = 0;
    int minAbs = Integer.MAX_VALUE;
    while (i < a.length && j < b.length) {
        if (a[i] < b[j]) {
            minAbs = Math.min(minAbs, b[j] - a[i]);
            ++i;
        } else if (a[i] > b[j]){
            minAbs = Math.min(minAbs, a[i] - b[j]);
            ++j;
        } else {  // cannot be smaller
            minAbs = 0;
            break;
        }
    }
    return minAbs;
}

public static int findMinDiff(int[] array1, int[] array2)



{



int i = 0, j = 0;



int minDiff = Integer.MAX_VALUE;



 



while ( i < array1.length && j < array2.length )



{



if( array1[i] == array2[j] )



return 0;



 



int diff = Math.abs( array1[i] - array2[j] );



minDiff = Math.min( diff, minDiff );



 



if( array1[i] > array2[j] )



j++;



else



i++;



 



}



 



if( i < array1.length ) //array1 has some more elements



{



j--; // j has reached the end, move it to last element



while ( i < array1.length )



{



int diff = Math.abs( array1[i] - array2[j] );



minDiff = Math.min( diff, minDiff );



i++;



}



}



else //array2 has some more elements



{



i--;



while ( j < array2.length )



{



int diff = Math.abs( array1[i] - array2[j] );



minDiff = Math.min( diff, minDiff );



j++;



}



}



return minDiff;



}

http://www.zrzahid.com/smallest-difference-between-2-elements-from-2-different-array/

Given two arrays. Find the smallest difference between two elements from both of the arrays.

For example: A=[0, -6, 4, 6, 5, -2], and A=[-4, 8, 2, 3, 10, 9] then then the smallest difference between two elements of the two array is 1 with pairs (4, 3) from the arrays repectively.

Approach 1: w/o sorting
It’ll be O(n^2) as we need to iterate the 2nd list for each element of 1st list.

Approach 2: with sorting

public static int minDiffElements(int a1[], int a2[]){
 int minDiff = Integer.MAX_VALUE;
 int min1 = -1;
 int min2 = -1;
 int i = 0;
 int j = 0;
 int n1 = a1.length;
 int n2 = a2.length;
 int diff = 0;
 
 Arrays.sort(a1);//\\
 Arrays.sort(a2);
 while(i < n1 && j < n2){
  diff = Math.abs(a1[i]-a2[j]);
  if(diff < minDiff){
   minDiff = diff;
   min1 = a1[i];
   min2 = a2[j];
  }
  
  if(a1[i] < a2[j]){
   i++;
  }
  else{
   j++;
  }
 }
 
 System.out.println("min diff between two array elements: between "+min1+" and "+min2+" min diff: "+minDiff);
 return minDiff;
}

http://www.jiuzhang.com/qa/669/
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