【剑指offer】构建乘积数组

【书上的题解真妙】

public class Solution {
    public int[] multiply(int[] A) {
        if (A == null || A.length <= 0) {
            return null;
        }

        int[] C = new int[A.length];
        C[0] = 1;
        for (int i = 1; i < C.length; i++) {
            C[i] = C[i - 1] * A[i - 1];
        }

        int[] D = new int[A.length];
        D[D.length - 1] = 1;
        for (int i = D.length - 2; i >= 0; i--) {
            D[i] = D[i + 1] * A[i + 1];
        }

        int[] result = new int[A.length];
        for (int i = 0; i < result.length; i++) {
            result[i] = C[i] * D[i];
        }
        return result;
    }

}