寒假集训作业（7）——排序查找

利用STL库进行的查找：

#include <string>
#include <list>
#include <algorithm>
#include <iostream>
using namespace std;
int a[100010],b[100010];
int main()
{
    list <int> search;
    list <int>::iterator searcher;
    int n,m,temp1,temp2;
    cin>>n>>m;
    for(int i=0;i<=n-1;i++)
    {
        temp1=0;
        cin>>temp1;
        search.push_back(temp1);
    }
    for(int i=0;i<=m-1;i++)
    {
        temp2=0;
        cin>>temp2;
        searcher=find(search.begin(),search.end(),temp2);
        if (searcher == search.end())
        {
            cout << "NO" << endl;
        }
        else
        {
            cout << "YES" << endl;
        }
    }
}

以上的代码又可以当作模板。大概测试了一下，100000组数据，查找100000个，只需十秒。但仍然超时= =

以下是hash查找，即把需要查找的数字作为新数组hash的下标

#include <stdio.h>  
const int maxn = 1000001;  
int hash[maxn];  
int main()  
{  
    int t,m;  
    scanf("%d %d", &t, &m);  
    for(int i = 0; i < t; i++)  
    {  
        int n;  
        scanf("%d", &n);  
        hash[n]++;  
    }  
    for(int i = 0; i < m; i++)  
    {  
        int n;  
        scanf("%d", &n);  
        if(hash[n])  
        {  
            puts("YES");  
        }  
        else puts("NO");  
    }  
    return 0;  
}

#include<string.h>
#include<iostream>
using namespace std;
int main()
{
    int i,j,p,k,length;
    char s[110];
    while(cin>>s)
    {
        k=0;
        length=strlen(s);
        for(i=k; i<length; i++)
        {
            if(s[k]<s[i])k=i;
        }
        for(j=0; j<=k; j++)
            cout<<s[j];
        cout<<"(max)";
        for(i=k+1; i<length; i++)
        {
            if(s[i]==s[k])
            {
               cout<<s[i];
               cout<<"(max)";
            }
            else cout<<s[i];
        }
        cout<<endl;
    }
}

求最大元素（ASCII）

排序问题 猥琐龌龊淫荡的浪川把时间限定到了15ms，用cin竟然总是25ms，以后还是改用scanf吧= =

模板是MoreWindows写的，链接如下：

http://blog.csdn.net/morewindows/article/details/6678165

#include <iostream>
#include <algorithm>
#include <functional>
#include <cstdio>
using namespace std;
int a[1000010];
//将有二个有序数列a[first...mid]和a[mid...last]合并。
void mergearray(int a[], int first, int mid, int last, int temp[])
{
	int i = first, j = mid + 1;
	int m = mid,   n = last;
	int k = 0;

	while (i <= m && j <= n)
	{
		if (a[i] >= a[j])
			temp[k++] = a[i++];
		else
			temp[k++] = a[j++];
	}

	while (i <= m)
		temp[k++] = a[i++];

	while (j <= n)
		temp[k++] = a[j++];

	for (i = 0; i < k; i++)
		a[first + i] = temp[i];
}
void mergesort(int a[], int first, int last, int temp[])
{
	if (first < last)
	{
		int mid = (first + last) / 2;
		mergesort(a, first, mid, temp);    //左边有序
		mergesort(a, mid + 1, last, temp); //右边有序
		mergearray(a, first, mid, last, temp); //再将二个有序数列合并
	}
}

/*bool MergeSort(int a[], int n)
{
	int *p = new int[n];
	if (p == NULL)
		return false;
	mergesort(a, 0, n - 1, p);
	delete[] p;
	return true;
}*/


int temp[1000010];
int main()
{
    //freopen("D:\\aaa.txt","r",stdin);
    //freopen("D:\\ans2.txt","w",stdout);
    int n;
    while(~scanf("%d",&n))
    {
        for(int i=0;i<=n-1;i++)
        {
           scanf("%d",&a[i]);
        }
        mergesort(a,0,n+1,temp);
        //sort(a,a+n+1,greater<int>());
        for(int i=0;i<=n-1;i++)
        {
            if(i!=n-1) printf("%d ",a[i]);
            else printf("%d\n",a[i]);
        }
    }
}

经测试，sort 跟mergesort在这组数据中是差不多的。