Introduction
一个 k 镜像数字 指的是一个在十进制和 k 进制下从前往后读和从后往前读都一样的没有前导0的正整数。
比方说，9 是一个 2 镜像数字。9 在十进制下为 9 ，二进制下为 1001 ，两者从前往后读和从后往前读都一样。
相反地，4 不是一个 2 镜像数字。4 在二进制下为 100 ，从前往后和从后往前读不相同。
给你进制 k 和一个数字n，请你返回k镜像数字中最小的n 个数之和。
Input
给定两个整数k和n，其中k(2 <= k <= 9)，n（1 <= n <= 30）。
Output
对于输入的k和n，返回题目所要求的k镜像中最小的n个数之和。
Sample
input
2 5
output
25
Solution
import java.util.Scanner; public class Main { public static void main(String[] args) { Scanner s=new Scanner(System.in); int k=s.nextInt();int n=s.nextInt(); long [][] nums = {{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, {0, 1, 4, 9, 16, 25, 58, 157, 470, 1055, 1772, 9219, 18228, 33579, 65802, 105795, 159030, 212865, 286602, 872187, 2630758, 4565149, 6544940, 9674153, 14745858, 20005383, 25846868, 39347399, 759196316L, 1669569335L, 2609044274L}, {0, 1, 3, 7, 15, 136, 287, 499, 741, 1225, 1881, 2638, 31730, 80614, 155261, 230718, 306985, 399914, 493653, 1342501, 2863752, 5849644, 9871848, 14090972, 18342496, 22630320, 28367695, 36243482, 44192979, 71904751, 155059889L}, {0, 1, 3, 6, 11, 66, 439, 832, 1498, 2285, 3224, 11221, 64456, 119711, 175366, 233041, 739646, 2540727, 4755849, 8582132, 12448815, 17500320, 22726545, 27986070, 33283995, 38898160, 44577925, 98400760, 721411086L, 1676067545L, 53393239260L}, {0, 1, 3, 6, 10, 16, 104, 356, 638, 1264, 1940, 3161, 18912, 37793, 10125794, 20526195, 48237967, 78560270, 126193944, 192171900, 1000828708L, 1832161846L, 2664029984L, 3500161622L, 4336343260L, 6849225412L, 9446112364L, 12339666346L, 19101218022L, 31215959143L, 43401017264L}, {0, 1, 3, 6, 10, 15, 22, 77, 188, 329, 520, 863, 1297, 2074, 2942, 4383, 12050, 19827, 41849, 81742, 156389, 325250, 1134058, 2043967, 3911648, 7009551, 11241875, 15507499, 19806423, 24322577, 28888231}, {0, 1, 3, 6, 10, 15, 21, 29, 150, 321, 563, 855, 17416, 83072, 2220384, 6822448, 13420404, 20379000, 29849749, 91104965, 321578997L, 788407661L, 1273902245L, 1912731081L, 2570225837L, 3428700695L, 29128200347L, 69258903451L, 115121130305L, 176576075721L, 241030621167L}, {0, 1, 3, 6, 10, 15, 21, 28, 37, 158, 450, 783, 1156, 1570, 2155, 5818, 14596, 27727, 41058, 67520, 94182, 124285, 154588, 362290, 991116, 1651182, 3148123, 5083514, 7054305, 11253219, 66619574}, {0, 1, 3, 6, 10, 15, 21, 28, 36, 227, 509, 882, 1346, 1901, 2547, 3203, 10089, 35841, 63313, 105637, 156242, 782868, 2323319, 4036490, 5757761, 7586042, 9463823, 11349704, 13750746, 16185088, 18627530}}; System.out.println(nums[k][n]); } }
Experience
第一次做到这种类型的题目，感觉这种小套路实在好玩又好用。怎么能这么出题呢？（
