算法学习之百钱买百鸡
?? 百錢買百雞的問題算是一套非常經典的不定方程的問題,題目很簡單:公雞5文錢一只,母雞3文錢一只,小雞3只一文錢,
用100文錢買一百只雞,其中公雞,母雞,小雞都必須要有,問公雞,母雞,小雞要買多少只剛好湊足100文錢。
~~~~~~~~~
#include <stdio.h>
#include <stdlib.h>
int main(void)
{
??? int i=0,j=0,k=0;
??? for (i=1;i<20;i++){
??????? n=n++;
??????? for (j=1;j<33;j++){
??????????? n=n++;
??????????? k = 100-i-j;
??????????? if (i*5+j*3+ k/3 == 100 && k%3 == 0){
??????????????? printf("the value of cock is:%d\n",i);
??????????????? printf("the value of hen is:%d\n",j);
??????????????? printf("the value of chicken is:%d\n",k);
??????????????? printf("~~~~~~~~~~~~~~~~~~~~~~~~~~\n");
??????????? }
??????? }
??? }
???
?printf("the total of count is:%d\n",n);
system("pause");
return 0;
}
時間復雜度為O(N2),
優化一點如下,記數器從627變為310:
#include <stdio.h>
#include <stdlib.h>
int main(void)
{
??? int i=0,j=0,k=0,n=0;
??? for (i=1;i<20;i++){
??????? n=n++;
??????? for (j=1;j<((100-5*i)/3);j++){
??????????? n=n++;
??????????? k = 100-i-j;
??????????? if (i*5+j*3+ k/3 == 100 && k%3 == 0){
??????????????? printf("the value of cock is:%d\n",i);
??????????????? printf("the value of hen is:%d\n",j);
??????????????? printf("the value of chicken is:%d\n",k);
??????????????? printf("~~~~~~~~~~~~~~~~~~~~~~~~~~\n");
??????????? }
??????? }
??? }
???
?printf("the total of count is:%d\n",n);
system("pause");
return 0;
}
如果要成為O(N),則先用方程式多推導,這才是算法的精華。。
先在頭腦中過濾,再交給CPU,內存去實施~~
抄其它人的算法如下:
????????????? for (int k = 1; k <= 3; k++)
???????????????? x = 4 * k;
???????????????? y = 25 - 7 * k;
??????????????? ?z = 75 + 3 * k;
推薦BLOG:
http://www.cnblogs.com/huangxincheng/category/401959.html
http://www.cnblogs.com/vamei/default.html?page=1
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