SQRT分解

SQRT分解

Leetcode303

import java.util.Arrays;

public class NumArray {
    private int[] data, blocks;
    private int N;//元素总数
    private int B;//每组元素个数
    private int Bn;//组数
    public NumArray(int[] nums) {
        N = nums.length;
        if (N == 0) {
            return;
        }
        B = (int) Math.sqrt(N);
        Bn = N / B + (N % B > 0 ? 1 : 0);
        data = Arrays.copyOf(nums, N);
        blocks = new int[Bn];
        for (int i = 0; i < N; i++) {
            blocks[i / B] += nums[i];
        }
    }

    public int sumRange(int x, int y) {
        if (x < 0 || x >= N || y < 0 || y >= N || x > y) {
            return 0;
        }
        int bstart = x / B, bend = y / B;
        int res = 0;
        if (bstart == bend) {
            for (int i = x; i <= y; i++) {
                res += data[i];
            }
            return res;
        }
        for (int i = x; i < (bstart + 1) * B; i++) {
            res += data[i];
        }
        for (int b = bstart + 1; b < bend; b++) {
            res += blocks[b];
        }
        for (int i = bend * B; i <= y; i++) {
            res += data[i];
        }
        return res;
    }
}

Docker

学习了dockers，并且完成了安装并且对docker进行了简单的应用。