STL的其他用法（adjacent_find, find_first_of, sort_heap, merge, binary_search）总结

2017-08-20 17:26:07

writer：pprp

1、adjacent_find()

下面是源码实现：

template <class ForwardIterator>
ForwardIterator adjacent_find (ForwardIterator first, ForwardIterator last)
{
  if (first != last)
  {
    ForwardIterator next=first; ++next;
    while (next != last) {
      if (*first == *next)     // or: if (pred(*first,*next)), for version (2)
        return first;
      ++first; ++next;
    }
  }
  return last;
}

测试：

/*
name : STL的其他用法
writer : pprp
declare : null
date ； 2017/8/20
*/
#include <bits/stdc++.h>

using namespace std;
typedef list<int> LIST;

bool Equal(int a, int b)
{
      return (a - b)%2 == 0?1:0;
}

void print(LIST&q)
{
     LIST::iterator it;
     for(it = q.begin() ; it != q.end(); it++) 
     {
           cout << *it << " ";
     }
     cout << endl;
}

int main()
{
      //adjacent_find 查找相邻元素
      LIST l;
      
      for(int i = 0 ; i < 10 ; i++)
      {
            l.push_back(i);
            l.push_back(i+1);
            l.push_back(i+1);
            l.push_back(i+2);
      }
      l.push_back(93);
      l.push_back(5);
      l.push_back(5);
      l.push_back(2);
      l.push_back(2);
      l.push_back(33);
      l.push_back(52);
      l.push_back(12);
      l.push_back(18);
      
      print(l);
      
      LIST::iterator it = adjacent_find(l.begin(),l.end());
      
      if(it != l.end())
      {
            cout << "两个相邻元素相等" << *it << " ";
            it++;
            cout << *it << endl;
      }
      
      list <int>::iterator ii = adjacent_find(l.begin(), l.end(), Equal);
      if(ii != l.end())
      {
            cout <<"找出首个两个相邻元素相同"<< *ii << " ";
            ii++;
            cout << *ii << endl;
      }
      
      return 0;
}

2、find_first_of查找第一个匹配字符串(不推荐使用，查看源代码采用最高复杂度的算法)

/*
name : STL的其他用法:find_first_of
writer : pprp
declare : null
date ； 2017/8/20
*/
#include <bits/stdc++.h>

using namespace std;

int main()
{
      char * s1 = "abcdefu7ghijklmn";
      char * s2 = "zyx3yu7ys";
      char * i = find_first_of(s1,s1 + strlen(s1),s2,s2 + strlen(s2));   
      //第一个出现在s2中的字符为 *i
      cout << * i << endl;
      return 0;
}

3、堆排序（有点慢）

/*
name : STL中的堆排序
writer : pprp
declare : 复杂度为 nlogn
date ； 2017/8/20
*/
#include <bits/stdc++.h>
#include <cstdio>
#include <cstdlib>
#include <ctime>
#include <vector>

using namespace std;

void print(int x)
{
      cout << x << " ";
}

int main()
{
      vector<int> v;
      int tmp;
      //每次执行的种子不同，生成的随机数才不相同
      srand((int)time(NULL));
      //产生10个随机数，记录在vector中
      for(int i = 0 ; i < 10 ; i++)
      {
           tmp = rand() % 100; 
           v.push_back(tmp);
      } 
      
      for_each(v.begin(), v.end(),print);
      cout << endl;
      
      make_heap(v.begin(),v.end());
      sort_heap(v.begin(),v.end());
      
      for_each(v.begin(),v.end(),print);
      cout << endl;
      
      return 0;
}

4、归并算法（合并两个有序的序列）

/*
name : 归并排序，合并两个有序序列
writer : pprp
declare : 复杂度为 nlogn
date ； 2017/8/20
*/
#include <bits/stdc++.h>
#include <cstdio>
#include <cstdlib>
#include <ctime>

using namespace std;
const int maxn = 100;
int a[maxn];
int b[maxn];

void print(int *x,int n)
{
    for(int i = 0 ; i < n ; i++)
    {
        cout << x[i] << " ";
    }
    cout << endl;
}

int main()
{
    srand((int)time(NULL));
    //产生10个随机数，记录在vector中
    for(int i = 0 ; i < 6 ; i++)
    {
        a[i] = rand()%100;
        b[i] = rand()%100;
    }
    //升序
    sort(a,a+6);
    sort(b,b+6);
    
    print(a,6);
    print(b,6);
    
    int result[maxn*2];
    
    merge(a,a+6,b,b+6,result,less<int>());
    
    print(result,12);
    
    //降序
    sort(a,a+6,greater<int>());
    sort(b,b+6,greater<int>());
    
    merge(a,a+6,b,b+6,result,greater<int>());
    
    print(result,12);

    return 0;
}

5、binary_search折半查找（用在有序区间中）

bool binary_search(a,a+size,key)

6、includes判断集合包含关系

int a[5] = {0,2,5,12,54};
int b[10] = {12,32,34,54,6,34,54,23,2,24};

if(includes(a,a+5,b,b+5))
{
    cout << "yes" << endl;
}
else
{
    cout << "no" << endl;
}

7、最值

max(12,321);
min(21,32);
//查找线性容器中的最大最小
list <int> :: iterator it = min_element(l.begin(), l.end());
list <int> :: iterator it = max_element(l.begin(), l.end());
//字典序比较大小
lexicographical_compare(s1,s1+len1,s2,s2+len2);

 8、组合数生成

/*
name : STL中的堆排序
writer : pprp
declare : 复杂度为 nlogn
date ； 2017/8/20
*/
#include <bits/stdc++.h>
#include <cstdio>
#include <cstdlib>
#include <ctime>

using namespace std;

void print(int a[])
{
      for(int i = 0; i < 5 ; i++)
      {
            cout << a[i] << " ";
      }
      cout << endl;
}

int main()
{
      int a[] = {3,5,6,7,9};
      while(next_permutation(a,a+5))
      {
            print(a);
      }
      cout << endl;
      
      while(prev_permutation(a,a+5))
      {
            print(a);
      }
      
      return 0;
}