Algorithm常用函数（1）

1.求和——accumulate

#include<iostream>
#include<cstring>
#include<cstdio>

#include<numeric>//accumulate
using namespace std;

int main()
{
int all[100] = {2,2,3,4,5,6,7,8,9,10};
int sum = accumulate(all, all + 3, 1);//all的前三个数相加，和的初始值是1
printf("%d", sum);

return 0;
}

2.二分查找—— binary_search

#include<algorithm>
#include<numeric>

using namespace std;

int main()
{
int all[100] = {0, 1, 2, 3, 4, 5, 89, 104, 300, 600, 9000};
int a;

while(scanf_s("%d", &a, 1) != EOF)
{
if(binary_search(all, all + 10, a))//在all的前十个元素中搜索a
printf_s("Have\n");
else
printf_s("Not have\n");
}

return 0;
}

3.拷贝函数——copy与copy_backward

#include<cstdio>
#include<iostream>
#include<cstring>

///copy
#include<algorithm>
#include<numeric>
using namespace std;

class N
{
public:
int a;
int b;
int c;
}all1[100], all2[100];

int main()
{
all1[0].a = 1;
all1[0].b = 2;
all1[0].c = 3;

all1[1].a = 4;
all1[1].b = 5;
all1[1].c = 6;

copy(all1, all1 + 2, all2);//copy_backward

for(int i = 0 ; i < 2 ; i ++)
{
printf_s("%d\t%d\t%d\n", all2[i].a, all2[i].b, all2[i].c);
}

return 0;
}

4. 计数——count

#include<cstdio>
#include<cstring>
#include<iostream>

//count
#include<algorithm>
#include<numeric>

using namespace std;

int main()
{
int all[11] = {0, 1, 0, 0, 1, 0, 1, 5, 1, 0, 0};

int num = count(all, all + 8, 5);//数一下all的前八个数里面1的个数
printf_s("%d\n", num);

return 0;
}

5. 条件计数——count_if

#include<cstdio>
#include<iostream>
#include<cstring>

//count_if
#include<algorithm>
#include<numeric>

using namespace std;

int main()
{
int all[11] = {0, 1, 2, 3, 4, 5, 6, 4, 5, 6, 10};
int sum = count_if(all, all + 11,bind2nd(equal_to<int>(), 5));//这种方法貌似是被遗弃鸟~~

printf_s("%d", sum);

return 0;
}

6. 相等——equal

#include<cstdio>
#include<iostream>
#include<cstring>

//equal
#include<algorithm>
#include<numeric>

using namespace std;

int main()
{
int all[11]={0,1,2,3,4,5,6,7,8,9,10};
int all2[11]={0,1,2,3,4,5,6,7,8,9,11};
if(equal(all, all + 10, all2))//比较all与all2的前10个元素是否相等，可以扩展到对象是否相等
printf_s("equal\n");
else
printf_s("not equal\n");

return 0;
}

7. 填充——fill，fill_n

#include<cstdio>
#include<iostream>
#include<cstring>

//fill，fill_n
#include<algorithm>
#include<numeric>

using namespace std;

int main()
{
int all[11] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10};

//fill(all, all + 11 , 100);//将all的前11个元素填充成100
fill_n(all, 5, 100);//前5个元素填充成100，其他不变
printf_s("%d\n", all[4]);
printf_s("%d\n", all[5]);
}

8. 查找——find，find_end，find_first_of，find_if

#include<cstdio>
#include<cstring>
#include<iostream>

//find，find_end，find_first_of，find_if
#include<algorithm>
#include<numeric>

using namespace std;

int main()
{
int all[14]={0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 4, 5, 6};
int *a = find(all, all + 11, 8);//在all的前11个元素中查找8，如果存在，则返回8所对应的指针
printf_s("%d\n", *a);

int all2[4] = {4, 5, 6};
a = find_end(all, all + 14, all2 + 0 , all2 + 3);//找到字串all2在all中最后出现的初始位置
printf_s("位置：%d\n", a - all);

a = find_first_of(all, all + 14, all2 + 0 , all2 + 3);//找到字串all2在all中第一次出现的初始位置
printf_s("位置：%d\n", a - all);

int *sum=find_if(all,all+10,bind2nd(greater_equal<int> (), 5));//这种方法被遗弃了
printf("%d",sum-all);

return 0;
}