Where is the Marble?（STL）

Where is the Marble?

Raju and Meena love to play with Marbles. They have got a lot of marbles with numbers written on them. At the beginning, Raju would place the marbles one after another in ascending order of the numbers written on them. Then Meena would ask Raju to find the first marble with a certain number. She would count 1...2...3. Raju gets one point for correct answer, and Meena gets the point if Raju fails. After some fixed number of trials the game ends and the player with maximum points wins. Today it's your chance to play as Raju. Being the smart kid, you'd be taking the favor of a computer. But don't underestimate Meena, she had written a program to keep track how much time you're taking to give all the answers. So now you have to write a program, which will help you in your role as Raju.

Input 

There can be multiple test cases. Total no of test cases is less than 65. Each test case consists begins with 2 integers: N the number of marbles and Q the number of queries Mina would make. The next N lines would contain the numbers written on the N marbles. These marble numbers will not come in any particular order. Following Qlines will have Q queries. Be assured, none of the input numbers are greater than 10000 and none of them are negative.

Input is terminated by a test case where N = 0 and Q = 0.

Output 

For each test case output the serial number of the case.

For each of the queries, print one line of output. The format of this line will depend upon whether or not the query number is written upon any of the marbles. The two different formats are described below:

• `x found at y', if the first marble with number x was found at position y. Positions are numbered 1, 2,..., N.
• `x not found', if the marble with number x is not present.

Look at the output for sample input for details.

Sample Input 

4 1
2
3
5
1
5
5 2
1
3
3
3
1
2
3
0 0

Sample Output 

CASE# 1:
5 found at 4
CASE# 2:
2 not found
3 found at 3

输出输入的数字在数组中的位置

lower_bound(数组的开始位置,结束位置,查找的数据)

#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
int main()
{
    int N,Q,index,s=0;
    int a[10000];
    int b[10000];
    while(scanf("%d%d",&N,&Q)!=EOF)
    {
        if(N+Q==0)
            break;
        memset(a,0,sizeof(a));
        for(int i=0;i<N;i++)
            scanf("%d",&a[i]);
        sort(a,a+N);
        memset(b,0,sizeof(b));
        for(int i=0;i<Q;i++)
        {
            scanf("%d",&b[i]);
        }
        printf("CASE# %d:\n",++s);
        for(int i=0;i<Q;i++)
          {
              index=lower_bound(a,a+N,b[i])-a;
              if(a[index]==b[i])
                 printf("%d found at %d\n",b[i],index+1);
              else
                 printf("%d not found\n",b[i]);
          }
     }
     return 0;
}

 lower_bound算法返回一个非递减序列[first, last)中的第一个大于等于值val的位置。

upper_bound算法返回一个非递减序列[first, last)中第一个大于val的位置。如下图所示：

 

 lower_bound:

int lower_bound(int *array, int size, int key)
{
    int first = 0, middle;
    int half, len;
    len = size;
 
    while(len > 0) {
        half = len >> 1;
        middle = first + half;
        if(array[middle] < key) {     
            first = middle + 1;          
            len = len-half-1;       //在右边子序列中查找
        }
        else
            len = half;            //在左边子序列（包含middle）中查找
    }
    return first;
}

unper_bound：

int upper_bound(int *array, int size, int key)
{
    int first = 0, len = size-1;
    int half, middle;
 
    while(len > 0){
        half = len >> 1;
        middle = first + half;
        if(array[middle] > key)     //中位数大于key,在包含last的左半边序列中查找。
            len = half;
        else{
            first = middle + 1;    //中位数小于等于key,在右半边序列中查找。
            len = len - half - 1;
        }
    }
    return first;
}