The Smallest Difference

Given two array of integers(the first array is array A, the second array is arrayB), now we are going to find a element in array A which is A[i], and another element in array B which is B[j], so that the difference between A[i] and B[j] (|A[i] - B[j]|) is as small as possible, return their smallest difference.

Example

For example, given array A = [3,6,7,4], B = [2,8,9,3], return 0。

分析：

首先sort, 然后用两个指针分别指向两个array的头部，谁小移动谁。

public class Solution {
    /**
     * @param A, B: Two integer arrays.
     * @return: Their smallest difference.
     */
    public int smallestDifference(int[] A, int[] B) {
        Arrays.sort(A);
        Arrays.sort(B);
        
        int pa = 0; 
        int pb = 0;
        
        int diff = Integer.MAX_VALUE;
        
        while (pa < A.length && pb < B.length) {
            if (A[pa] < B[pb]) {
                diff = Math.min(diff, Math.abs(A[pa] - B[pb]));
                pa++;
            } else if (A[pa] == B[pb]) {
                return 0;
            } else {
                diff = Math.min(diff, Math.abs(A[pa] - B[pb]));
                pb++;
            }
        }
        return diff;
    }
}