题目
标题：兴趣小组
为丰富同学们的业余文化生活，某高校学生会创办了3个兴趣小组 （以下称A组，B组，C组）。
每个小组的学生名单分别在【A.txt】,【B.txt】和【C.txt】中。 每个文件中存储的是学生的学号。由于工作需要，我们现在想知道：
既参加了A组，又参加了B组，但是没有参加C组的同学一共有多少人？请你统计该数字并通过浏览器提交答案。
注意：答案是一个整数，不要提交任何多余的内容。
笨笨有话说：
哇塞！数字好多啊！一眼望过去就能发现相同的，好像没什么指望。 不过，可以排序啊，要是每个文件都是有序的，那就好多了。歪歪有话说：
排什么序啊，这么几行数字对计算机不是太轻松了吗？
我看着需求怎么和中学学过的集合很像啊…
过程
public class action1 {
public static void main(String[] args) {
int a[] = { 12894792, 92774113, 59529208, 22962224, 2991600, 83340521,
87365045, 40818286, 16400628, 39475245, 55933381, 76940287,
61366748, 95631228, 17102313, 50682833, 61562613, 87002524,
83062019, 51743442, 61977890, 32010762, 69680621, 87179571,
81761697, 32364296, 7833271, 36198035, 26588918, 84046668,
43059468, 73191775, 56794101, 454780, 11141030, 10008994,
35072237, 44945158, 53959980, 75758119, 18560273, 35801494,
42102550, 22496415, 3981786, 34593672, 13074905, 07733442,
42374678, 23452507, 98586743, 30771281, 17703080, 52123562,
5898131, 56698981, 90758589, 18238802, 18217979, 4511837,
75682969, 31135682, 55379006, 42224598, 98263070, 40228312,
28924663, 11580163, 25686441, 45944028, 96731602, 53675990,
3854194, 14858183, 16866794, 40677007, 73141512, 32317341,
56641725, 43123040, 15201174, 62389950, 72887083, 76860787,
61046319, 6923746, 17874548, 46028629, 10577743, 48747364,
5328780, 59855415, 60965266, 20592606, 14471207, 70896866,
46938647, 33575820, 53426294, 56093931, 51326542, 94050481,
80114017, 33010503, 72971538, 22407422, 17305672, 78974338,
93209260, 83461794, 41247821, 26118061, 10657376, 42198057,
15338224, 50284714, 32232841, 26716521, 76048344, 23676625,
62897700, 69296551, 59653393, 38704390, 48481614, 69782897,
26850668, 37471053, 88720989, 51010849, 94951571, 60024611,
29808329, 70377786, 13899299, 9683688, 58218284, 46792829,
97221709, 45286643, 48158629, 57367208, 26903401, 76900414,
87927040, 9926730, 1508757, 15101101, 62491840, 43802529 };
int b[] = { 44894050, 34662733, 44141729, 92774113, 99208727, 91919833,
23727681, 10003409, 55933381, 54443275, 13584702, 96523685,
50682833, 61562613, 62380975, 20311684, 93200452, 23101945,
42192880, 28992561, 18460278, 19186537, 58465301, 1111066,
62680429, 23721241, 20277631, 91708977, 57514737, 3981786,
81541612, 7346443, 93154608, 19709455, 37446968, 17703080,
72378958, 66200696, 30610382, 89586343, 33152171, 67040930,
35696683, 63242065, 99948221, 96233367, 52593493, 98263070,
1418023, 74816705, 89375940, 58405334, 96731602, 84089545,
16866794, 94737626, 1673442, 70548494, 13638168, 8163691,
11106566, 64375392, 40267902, 897705, 56447313, 54532235,
94738425, 66642634, 83219544, 40546096, 66924991, 20592606,
96037590, 73434467, 70896866, 91025618, 57892091, 8487641,
32500082, 84412833, 23311447, 38380409, 79957822, 72971538,
69645784, 91863314, 73099909, 93209260, 83461794, 81378487,
30423273, 22233715, 32232841, 26716521, 3511221, 29196547,
58263562, 56233305, 52547525, 55812835, 87253244, 52484232,
80837360, 94098464, 52028151, 53267501, 66381929, 84381316,
59788467, 9683688, 67082008, 71605255, 80654064, 21434307,
45286643, 76556656, 82465821, 57367208, 79218980, 48460468,
59170479, 46046391, 43043164, 96544490, 83340521, 70837892,
18926791, 40818286, 28936302, 11489524, 51031183, 73860337,
13241219, 9025448, 10718828, 76360986, 26031606, 76558053,
97726139, 46473415, 48406387, 23625539, 86756012, 35164187,
49161302, 78082834, 35072237, 8602486, 29815841, 56562216,
77684187, 81751704, 20160464, 50407962, 27786415, 19893526,
934129, 37759498, 52636463, 25666982, 43262852, 38393436,
2581136, 29323250, 56950657, 5898131, 95286262, 75574581,
54057961, 6703896, 90758589, 57782642, 34492535, 41919697,
6395464, 10993500, 81212949, 34017532, 69569396, 99009936,
57129610, 67401593, 71044018, 62076698, 29533873, 71936325,
86874388, 26545032, 35695544, 30433724, 53127345, 72887083,
25390873, 63711546, 6923746, 27783723, 33199575, 35929698,
16491251, 18276792, 62744775, 92096155, 6336570, 56141974,
73007273, 31416832, 171057, 64176982, 46938647, 58460388,
69972026, 73724304, 27435484, 51568616, 15531822, 47788699,
11818851, 41594694, 83561325, 43107163, 56965375, 10557343,
26118061, 74650126, 90076467, 10657376, 49901436, 3425162,
61164599, 15797769, 5427896, 14444084, 36795868, 18079449,
59653393, 72942548, 6763077, 33895610, 94892653, 12085268,
65174140, 79567366, 23020126, 74290047, 13498869, 21696323,
27724594, 54941003, 38229841, 7050068 };
int c[] = { 13404901, 39952424, 47847739, 94939581, 13809950, 70966043,
11161555, 17102313, 47079425, 50682833, 74154313, 61562613,
93200452, 37103342, 18479435, 32502597, 36198035, 54210010,
73191775, 48358178, 85544503, 5996766, 54651623, 52113220,
27465181, 23871783, 22496415, 54107041, 65899605, 56528700,
82671109, 61176034, 42374678, 51612628, 63329997, 56591652,
4552733, 12789324, 89586343, 51935014, 38611966, 43916409,
70996050, 98263070, 1418023, 65345049, 21734275, 76846198,
71506230, 833171, 67128139, 41367555, 64769510, 44010700,
16475199, 93164325, 9386162, 95324041, 80688223, 67629139,
79552617, 76219736, 50368644, 45096021, 54972488, 63779011,
28862942, 73145521, 74078605, 66924991, 12806850, 2171001,
70896866, 73434467, 8487641, 44415025, 32500082, 84412833,
83896188, 52243759, 49191410, 38744339, 48079796, 44937032,
06267501, 81866886, 38575984, 25978688, 78974338, 41247821,
12356966, 64842303, 79127158, 2366944, 68000570, 12426275,
96409230, 705972, 8266503, 83820884, 8831807, 43273308,
23216105, 29196547, 95160161, 05553537, 52182214, 32641346,
91553427, 24436506, 77433749, 1979664, 52028151, 88985343,
1761499, 76203088, 63237368, 23405334, 59788467, 9683688,
67755443, 29946533, 12053603, 437479, 15200030, 45286643,
93537527, 82465821, 57367208, 53899751, 15354933, 97760830,
68933762, 80220545, 1892750, 39868288, 21524323, 69716610,
65083815, 78048499, 3227391, 83340521, 87365045, 71720254,
51031183, 89168555, 8503028, 37086236, 25103057, 87002524,
22808816, 80928090, 90741678, 15993372, 99117082, 49938176,
21755083, 86903426, 87830263, 53959980, 75758119, 59781354,
58679691, 25666982, 56307643, 47180521, 62776522, 78136608,
44882734, 90758589, 8075999, 66303819, 23480347, 11580163,
87080118, 18329165, 92514163, 89404632, 92377859, 3912329,
17499963, 59699979, 79876366, 63894807, 37857001, 86003935,
90087123, 29433345, 80298948, 61531153, 61046319, 37839841,
19421134, 48747364, 35196916, 62484573, 59907079, 36845702,
21631642, 72739317, 26283700, 80114017, 76639390, 29154110,
35159758, 47788699, 11818851, 56520669, 36396767, 36031167,
83817428, 10657376, 90076467, 14676452, 11024560, 16327605,
76048344, 14444084, 95452011, 99612346, 65172562, 84813675,
88618282, 38704390, 27998014, 63859011, 33787505, 60024611,
16229880, 13899299, 35240335, 29173227, 45036451, 66177893,
82658333, 43100730, 44520187, 74290047, 85013538, 9926730,
27724594, 95148523, 20503000, 64390907, 26006953, 98116293,
97457666, 29017396, 4634371, 70791589 };
int d[]=new int[300];
int sum = 0;
for (int i = 0; i < a.length; i++) {
for (int j = 0; j < b.length; j++) {
//AB相同sum++
if (a[i]==b[j]) {
sum++;
}
}
}
for (int i = 0; i < a.length; i++) {
for (int j = 0; j < b.length; j++) {
//AB两个相同
if (a[i]==b[j]) {
for (int j2 = 0; j2 < c.length; j2++) {
//c跟AB相同就减去
if (b[j]==c[j2]) {
sum--;
}
}
}
}
}
System.out.println(sum);
}
}
答案
20