题目

Time Limit: 1000 ms
Case Time Limit: 1000 ms
Memory Limit: 64 MB
Total Submission: 224
Submission Accepted: 86

Description

吃完草莓以后，机房的小伙伴们要开始做些运动。在ACM实验室里有N盏灯编号为1到N，起初都是开着的，从第一盏灯开始，凡是编号是一的倍数的灯的开关都要被按一遍（亮的变成暗的，暗的变成亮的），
然后到第二盏灯，凡是编号是二的倍数的灯的开关都要被按一遍，一直到第N盏灯，凡是编号是N的倍数的灯都要被按一遍。那么问题来了，在灯质量比较好的情况下，最后还有多少盏灯是亮着的。

Input

题目包括多组输入
只有一行，这一行只有一个数N，1<=N<=1000

Output

输出一行，这一行也只有一个数，就是亮着灯的个数

Sample Input

3

Sample Output

2

Hint

经过第一个灯的时候1，2,3号灯都按了依次，经过第二个灯的时候，2号灯按了一次，经过第三个灯的时候，3号灯按了一次，最后只有2，3灯还亮着。

题解

强行模拟即可，且数据量较小，可打表

代码

#include <cstdio>
#include <algorithm>
#include <cstring>
#include <cmath>
#include <string>
#include <iostream>
#include <vector>
#include <list>
#include <stack>
using namespace std;
 
#define REP(n) for(int o=0;o<n;o++)
 
int ans[] = {0,0,1,2,2,3,4,5,6,6,7,8,9,10,11,12,12,13,14,15,16,17,18,19,20,20,
21,22,23,24,25,26,27,28,29,30,30,31,32,33,34,35,36,37,38,39,40,41,42,42,43,
44,45,46,47,48,49,50,51,52,53,54,55,56,56,57,58,59,60,61,62,63,64,65,66,67,
68,69,70,71,72,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,90,
91,92,93,94,95,96,97,98,99,100,101,102,103,104,105,106,107,108,109,110,110,
111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,126,127,128,129,
130,131,132,132,133,134,135,136,137,138,139,140,141,142,143,144,145,146,147,
148,149,150,151,152,153,154,155,156,156,157,158,159,160,161,162,163,164,165,
166,167,168,169,170,171,172,173,174,175,176,177,178,179,180,181,182,182,183,
184,185,186,187,188,189,190,191,192,193,194,195,196,197,198,199,200,201,202,
203,204,205,206,207,208,209,210,210,211,212,213,214,215,216,217,218,219,220,
221,222,223,224,225,226,227,228,229,230,231,232,233,234,235,236,237,238,239,
240,240,241,242,243,244,245,246,247,248,249,250,251,252,253,254,255,256,257,
258,259,260,261,262,263,264,265,266,267,268,269,270,271,272,272,273,274,275,
276,277,278,279,280,281,282,283,284,285,286,287,288,289,290,291,292,293,294,
295,296,297,298,299,300,301,302,303,304,305,306,306,307,308,309,310,311,312,
313,314,315,316,317,318,319,320,321,322,323,324,325,326,327,328,329,330,331,
332,333,334,335,336,337,338,339,340,341,342,342,343,344,345,346,347,348,349,
350,351,352,353,354,355,356,357,358,359,360,361,362,363,364,365,366,367,368,
369,370,371,372,373,374,375,376,377,378,379,380,380,381,382,383,384,385,386,
387,388,389,390,391,392,393,394,395,396,397,398,399,400,401,402,403,404,405,
406,407,408,409,410,411,412,413,414,415,416,417,418,419,420,420,421,422,423,
424,425,426,427,428,429,430,431,432,433,434,435,436,437,438,439,440,441,442,
443,444,445,446,447,448,449,450,451,452,453,454,455,456,457,458,459,460,461,
462,462,463,464,465,466,467,468,469,470,471,472,473,474,475,476,477,478,479,
480,481,482,483,484,485,486,487,488,489,490,491,492,493,494,495,496,497,498,
499,500,501,502,503,504,505,506,506,507,508,509,510,511,512,513,514,515,516,
517,518,519,520,521,522,523,524,525,526,527,528,529,530,531,532,533,534,535,
536,537,538,539,540,541,542,543,544,545,546,547,548,549,550,551,552,552,553,
554,555,556,557,558,559,560,561,562,563,564,565,566,567,568,569,570,571,572,
573,574,575,576,577,578,579,580,581,582,583,584,585,586,587,588,589,590,591,
592,593,594,595,596,597,598,599,600,600,601,602,603,604,605,606,607,608,609,
610,611,612,613,614,615,616,617,618,619,620,621,622,623,624,625,626,627,628,
629,630,631,632,633,634,635,636,637,638,639,640,641,642,643,644,645,646,647,
648,649,650,650,651,652,653,654,655,656,657,658,659,660,661,662,663,664,665,
666,667,668,669,670,671,672,673,674,675,676,677,678,679,680,681,682,683,684,
685,686,687,688,689,690,691,692,693,694,695,696,697,698,699,700,701,702,702,
703,704,705,706,707,708,709,710,711,712,713,714,715,716,717,718,719,720,721,
722,723,724,725,726,727,728,729,730,731,732,733,734,735,736,737,738,739,740,
741,742,743,744,745,746,747,748,749,750,751,752,753,754,755,756,756,757,758,
759,760,761,762,763,764,765,766,767,768,769,770,771,772,773,774,775,776,777,
778,779,780,781,782,783,784,785,786,787,788,789,790,791,792,793,794,795,796,
797,798,799,800,801,802,803,804,805,806,807,808,809,810,811,812,812,813,814,
815,816,817,818,819,820,821,822,823,824,825,826,827,828,829,830,831,832,833,
834,835,836,837,838,839,840,841,842,843,844,845,846,847,848,849,850,851,852,
853,854,855,856,857,858,859,860,861,862,863,864,865,866,867,868,869,870,870,
871,872,873,874,875,876,877,878,879,880,881,882,883,884,885,886,887,888,889,
890,891,892,893,894,895,896,897,898,899,900,901,902,903,904,905,906,907,908,
909,910,911,912,913,914,915,916,917,918,919,920,921,922,923,924,925,926,927,
928,929,930,930,931,932,933,934,935,936,937,938,939,940,941,942,943,944,945,
946,947,948,949,950,951,952,953,954,955,956,957,958,959,960,961,962,963,964,
965,966,967,968,969,970,971,972,973,974};
 
int a(int N) {
    bool light[1010] = {0};
    for(int i = 1;i <= N;i++)
        for(int j = i;j <= N;j += i)
            light[j] = !light[j];
    int cnt = 0;
    REP(N) {
        if(!light[o + 1])
            cnt++;
    }
    return cnt;
}
 
int main() {
    int N;
    while(scanf("%d",&N) != EOF)
        printf("%d\n",ans[N]);
    return 0;
}