csdn 回文数

题目：
 Njzy学习了回文串后联想到了回文数，他希望统计出一个区间内的所有回文数。现在给定一个闭区间[a,b],求这个区间里有多少个回文数。
比如[20,30],只有一个回文数那就是22.
输入描述：
   输入包含多组测试数据，每组测试数据包含两个整数a,b,
   (0 输出描述：
   对于每组测试数据输出相应的答案。

分析：

100W以内的回文数只有1998个，所以我们可以考虑打表，然后二分查找a，b所处的位置，最后直接相减即可得到答案。

以下附上代码：

#include 
#include 
#include  

using namespace std;

const int maxn = 2000;

int cnt = 1998;
int table[maxn] = {1,2,3,4,5,6,7,8,9,11,22,33,44,55,66,77,88,99,101,111,121,131,141,151,161,171,181,191,202,212,222,232,242,252,262,272,282,292,303,313,323,333,343,353,363,373,383,393,404,414,424,434,444,454,464,474,484,494,505,515,525,535,545,555,565,575,585,595,606,616,626,636,646,656,666,676,686,696,707,717,727,737,747,757,767,777,787,797,808,818,828,838,848,858,868,878,888,898,909,919,929,939,949,959,969,979,989,999,1001,1111,1221,1331,1441,1551,1661,1771,1881,1991,2002,2112,2222,2332,2442,2552,2662,2772,2882,2992,3003,3113,3223,3333,3443,3553,3663,3773,3883,3993,4004,4114,4224,4334,4444,4554,4664,4774,4884,4994,5005,5115,5225,5335,5445,5555,5665,5775,5885,5995,6006,6116,6226,6336,6446,6556,6666,6776,6886,6996,7007,7117,7227,7337,7447,7557,7667,7777,7887,7997,8008,8118,8228,8338,8448,8558,8668,8778,8888,8998,9009,9119,9229,9339,9449,9559,9669,9779,9889,9999,10001,10101,10201,10301,10401,10501,10601,10701,10801,10901,11011,11111,11211,11311,11411,11511,11611,11711,11811,11911,12021,12121,12221,12321,12421,12521,12621,12721,12821,12921,13031,13131,13231,13331,13431,13531,13631,13731,13831,13931,14041,14141,14241,14341,14441,14541,14641,14741,14841,14941,15051,15151,15251,15351,15451,15551,15651,15751,15851,15951,16061,16161,16261,16361,16461,16561,16661,16761,16861,16961,17071,17171,17271,17371,17471,17571,17671,17771,17871,17971,18081,18181,18281,18381,18481,18581,18681,18781,18881,18981,19091,19191,19291,19391,19491,19591,19691,19791,19891,19991,20002,20102,20202,20302,20402,20502,20602,20702,20802,20902,21012,21112,21212,21312,21412,21512,21612,21712,21812,21912,22022,22122,22222,22322,22422,22522,22622,22722,22822,22922,23032,23132,23232,23332,23432,23532,23632,23732,23832,23932,24042,24142,24242,24342,24442,24542,24642,24742,24842,24942,25052,25152,25252,25352,25452,25552,25652,25752,25852,25952,26062,26162,26262,26362,26462,26562,26662,26762,26862,26962,27072,27172,27272,27372,27472,27572,27672,27772,27872,27972,28082,28182,28282,28382,28482,28582,28682,28782,28882,28982,29092,29192,29292,29392,29492,29592,29692,29792,29892,29992,30003,30103,30203,30303,30403,30503,30603,30703,30803,30903,31013,31113,31213,31313,31413,31513,31613,31713,31813,31913,32023,32123,32223,32323,32423,32523,32623,32723,32823,32923,33033,33133,33233,33333,33433,33533,33633,33733,33833,33933,34043,34143,34243,34343,34443,34543,34643,34743,34843,34943,35053,35153,35253,35353,35453,35553,35653,35753,35853,35953,36063,36163,36263,36363,36463,36563,36663,36763,36863,36963,37073,37173,37273,37373,37473,37573,37673,37773,37873,37973,38083,38183,38283,38383,38483,38583,38683,38783,38883,38983,39093,39193,39293,39393,39493,39593,39693,39793,39893,39993,40004,40104,40204,40304,40404,40504,40604,40704,40804,40904,41014,41114,41214,41314,41414,41514,41614,41714,41814,41914,42024,42124,42224,42324,42424,42524,42624,42724,42824,42924,43034,43134,43234,43334,43434,43534,43634,43734,43834,43934,44044,44144,44244,44344,44444,44544,44644,44744,44844,44944,45054,45154,45254,45354,45454,45554,45654,45754,45854,45954,46064,46164,46264,46364,46464,46564,46664,46764,46864,46964,47074,47174,47274,47374,47474,47574,47674,47774,47874,47974,48084,48184,48284,48384,48484,48584,48684,48784,48884,48984,49094,49194,49294,49394,49494,49594,49694,49794,49894,49994,50005,50105,50205,50305,50405,50505,50605,50705,50805,50905,51015,51115,51215,51315,51415,51515,51615,51715,51815,51915,52025,52125,52225,52325,52425,52525,52625,52725,52825,52925,53035,53135,53235,53335,53435,53535,53635,53735,53835,53935,54045,54145,54245,54345,54445,54545,54645,54745,54845,54945,55055,55155,55255,55355,55455,55555,55655,55755,55855,55955,56065,56165,56265,56365,56465,56565,56665,56765,56865,56965,57075,57175,57275,57375,57475,57575,57675,57775,57875,57975,58085,58185,58285,58385,58485,58585,58685,58785,58885,58985,59095,59195,59295,59395,59495,59595,59695,59795,59895,59995,60006,60106,60206,60306,60406,60506,60606,60706,60806,60906,61016,61116,61216,61316,61416,61516,61616,61716,61816,61916,62026,62126,62226,62326,62426,62526,62626,62726,62826,62926,63036,63136,63236,63336,63436,63536,63636,63736,63836,63936,64046,64146,64246,64346,64446,64546,64646,64746,64846,64946,65056,65156,65256,65356,65456,65556,65656,65756,65856,65956,66066,66166,66266,66366,66466,66566,66666,66766,66866,66966,67076,67176,67276,67376,67476,67576,67676,67776,67876,67976,68086,68186,68286,68386,68486,68586,68686,68786,68886,68986,69096,69196,69296,69396,69496,69596,69696,69796,69896,69996,70007,70107,70207,70307,70407,70507,70607,70707,70807,70907,71017,71117,71217,71317,71417,71517,71617,71717,71817,71917,72027,72127,72227,72327,72427,72527,72627,72727,72827,72927,73037,73137,73237,73337,73437,73537,73637,73737,73837,73937,74047,74147,74247,74347,74447,74547,74647,74747,74847,74947,75057,75157,75257,75357,75457,75557,75657,75757,75857,75957,76067,76167,76267,76367,76467,76567,76667,76767,76867,76967,77077,77177,77277,77377,77477,77577,77677,77777,77877,77977,78087,78187,78287,78387,78487,78587,78687,78787,78887,78987,79097,79197,79297,79397,79497,79597,79697,79797,79897,79997,80008,80108,80208,80308,80408,80508,80608,80708,80808,80908,81018,81118,81218,81318,81418,81518,81618,81718,81818,81918,82028,82128,82228,82328,82428,82528,82628,82728,82828,82928,83038,83138,83238,83338,83438,83538,83638,83738,83838,83938,84048,84148,84248,84348,84448,84548,84648,84748,84848,84948,85058,85158,85258,85358,85458,85558,85658,85758,85858,85958,86068,86168,86268,86368,86468,86568,86668,86768,86868,86968,87078,87178,87278,87378,87478,87578,87678,87778,87878,87978,88088,88188,88288,88388,88488,88588,88688,88788,88888,88988,89098,89198,89298,89398,89498,89598,89698,89798,89898,89998,90009,90109,90209,90309,90409,90509,90609,90709,90809,90909,91019,91119,91219,91319,91419,91519,91619,91719,91819,91919,92029,92129,92229,92329,92429,92529,92629,92729,92829,92929,93039,93139,93239,93339,93439,93539,93639,93739,93839,93939,94049,94149,94249,94349,94449,94549,94649,94749,94849,94949,95059,95159,95259,95359,95459,95559,95659,95759,95859,95959,96069,96169,96269,96369,96469,96569,96669,96769,96869,96969,97079,97179,97279,97379,97479,97579,97679,97779,97879,97979,98089,98189,98289,98389,98489,98589,98689,98789,98889,98989,99099,99199,99299,99399,99499,99599,99699,99799,99899,99999,100001,101101,102201,103301,104401,105501,106601,107701,108801,109901,110011,111111,112211,113311,114411,115511,116611,117711,118811,119911,120021,121121,122221,123321,124421,125521,126621,127721,128821,129921,130031,131131,132231,133331,134431,135531,136631,137731,138831,139931,140041,141141,142241,143341,144441,145541,146641,147741,148841,149941,150051,151151,152251,153351,154451,155551,156651,157751,158851,159951,160061,161161,162261,163361,164461,165561,166661,167761,168861,169961,170071,171171,172271,173371,174471,175571,176671,177771,178871,179971,180081,181181,182281,183381,184481,185581,186681,187781,188881,189981,190091,191191,192291,193391,194491,195591,196691,197791,198891,199991,200002,201102,202202,203302,204402,205502,206602,207702,208802,209902,210012,211112,212212,213312,214412,215512,216612,217712,218812,219912,220022,221122,222222,223322,224422,225522,226622,227722,228822,229922,230032,231132,232232,233332,234432,235532,236632,237732,238832,239932,240042,241142,242242,243342,244442,245542,246642,247742,248842,249942,250052,251152,252252,253352,254452,255552,256652,257752,258852,259952,260062,261162,262262,263362,264462,265562,266662,267762,268862,269962,270072,271172,272272,273372,274472,275572,276672,277772,278872,279972,280082,281182,282282,283382,284482,285582,286682,287782,288882,289982,290092,291192,292292,293392,294492,295592,296692,297792,298892,299992,300003,301103,302203,303303,304403,305503,306603,307703,308803,309903,310013,311113,312213,313313,314413,315513,316613,317713,318813,319913,320023,321123,322223,323323,324423,325523,326623,327723,328823,329923,330033,331133,332233,333333,334433,335533,336633,337733,338833,339933,340043,341143,342243,343343,344443,345543,346643,347743,348843,349943,350053,351153,352253,353353,354453,355553,356653,357753,358853,359953,360063,361163,362263,363363,364463,365563,366663,367763,368863,369963,370073,371173,372273,373373,374473,375573,376673,377773,378873,379973,380083,381183,382283,383383,384483,385583,386683,387783,388883,389983,390093,391193,392293,393393,394493,395593,396693,397793,398893,399993,400004,401104,402204,403304,404404,405504,406604,407704,408804,409904,410014,411114,412214,413314,414414,415514,416614,417714,418814,419914,420024,421124,422224,423324,424424,425524,426624,427724,428824,429924,430034,431134,432234,433334,434434,435534,436634,437734,438834,439934,440044,441144,442244,443344,444444,445544,446644,447744,448844,449944,450054,451154,452254,453354,454454,455554,456654,457754,458854,459954,460064,461164,462264,463364,464464,465564,466664,467764,468864,469964,470074,471174,472274,473374,474474,475574,476674,477774,478874,479974,480084,481184,482284,483384,484484,485584,486684,487784,488884,489984,490094,491194,492294,493394,494494,495594,496694,497794,498894,499994,500005,501105,502205,503305,504405,505505,506605,507705,508805,509905,510015,511115,512215,513315,514415,515515,516615,517715,518815,519915,520025,521125,522225,523325,524425,525525,526625,527725,528825,529925,530035,531135,532235,533335,534435,535535,536635,537735,538835,539935,540045,541145,542245,543345,544445,545545,546645,547745,548845,549945,550055,551155,552255,553355,554455,555555,556655,557755,558855,559955,560065,561165,562265,563365,564465,565565,566665,567765,568865,569965,570075,571175,572275,573375,574475,575575,576675,577775,578875,579975,580085,581185,582285,583385,584485,585585,586685,587785,588885,589985,590095,591195,592295,593395,594495,595595,596695,597795,598895,599995,600006,601106,602206,603306,604406,605506,606606,607706,608806,609906,610016,611116,612216,613316,614416,615516,616616,617716,618816,619916,620026,621126,622226,623326,624426,625526,626626,627726,628826,629926,630036,631136,632236,633336,634436,635536,636636,637736,638836,639936,640046,641146,642246,643346,644446,645546,646646,647746,648846,649946,650056,651156,652256,653356,654456,655556,656656,657756,658856,659956,660066,661166,662266,663366,664466,665566,666666,667766,668866,669966,670076,671176,672276,673376,674476,675576,676676,677776,678876,679976,680086,681186,682286,683386,684486,685586,686686,687786,688886,689986,690096,691196,692296,693396,694496,695596,696696,697796,698896,699996,700007,701107,702207,703307,704407,705507,706607,707707,708807,709907,710017,711117,712217,713317,714417,715517,716617,717717,718817,719917,720027,721127,722227,723327,724427,725527,726627,727727,728827,729927,730037,731137,732237,733337,734437,735537,736637,737737,738837,739937,740047,741147,742247,743347,744447,745547,746647,747747,748847,749947,750057,751157,752257,753357,754457,755557,756657,757757,758857,759957,760067,761167,762267,763367,764467,765567,766667,767767,768867,769967,770077,771177,772277,773377,774477,775577,776677,777777,778877,779977,780087,781187,782287,783387,784487,785587,786687,787787,788887,789987,790097,791197,792297,793397,794497,795597,796697,797797,798897,799997,800008,801108,802208,803308,804408,805508,806608,807708,808808,809908,810018,811118,812218,813318,814418,815518,816618,817718,818818,819918,820028,821128,822228,823328,824428,825528,826628,827728,828828,829928,830038,831138,832238,833338,834438,835538,836638,837738,838838,839938,840048,841148,842248,843348,844448,845548,846648,847748,848848,849948,850058,851158,852258,853358,854458,855558,856658,857758,858858,859958,860068,861168,862268,863368,864468,865568,866668,867768,868868,869968,870078,871178,872278,873378,874478,875578,876678,877778,878878,879978,880088,881188,882288,883388,884488,885588,886688,887788,888888,889988,890098,891198,892298,893398,894498,895598,896698,897798,898898,899998,900009,901109,902209,903309,904409,905509,906609,907709,908809,909909,910019,911119,912219,913319,914419,915519,916619,917719,918819,919919,920029,921129,922229,923329,924429,925529,926629,927729,928829,929929,930039,931139,932239,933339,934439,935539,936639,937739,938839,939939,940049,941149,942249,943349,944449,945549,946649,947749,948849,949949,950059,951159,952259,953359,954459,955559,956659,957759,958859,959959,960069,961169,962269,963369,964469,965569,966669,967769,968869,969969,970079,971179,972279,973379,974479,975579,976679,977779,978879,979979,980089,981189,982289,983389,984489,985589,986689,987789,988889,989989,990099,991199,992299,993399,994499,995599,996699,997799,998899,999999
};
int a,b;

int main(){
	while(scanf("%d%d",&a,&b) == 2){		
		printf("%d\n",upper_bound(table,table+cnt,b) - lower_bound(table,table+cnt,a));
	}
	return 0;
}