二分查找 BestCoder Round #36 ($) Gunner

题目传送门

 /*
     题意：问值为x的个数有几个，第二次查询就是0
     lower/upper_bound ()函数的使用，map也可过，hash方法不会
 */
 #include <cstdio>
 #include <cmath>
 #include <cstring>
 #include <algorithm>
 #include <iostream>
 #include <vector>
 #include <set>
 #include <map>
 #include <queue>
 using namespace std;

 const int MAXN = 1e6 + ;
 const int INF = 0x3f3f3f3f;
 int a[MAXN], b[MAXN];
 int used[MAXN];
 int n, m;

 inline int read(void)
 {
     int x = , f = ;    char ch = getchar ();
     while (ch < '' || ch > '')    {if (ch == '-') f = -;    ch = getchar ();}
     while (ch >= '' && ch <= '')    {x = x *  + ch - '';    ch = getchar ();}
     return f * x;
 }

 int main(void)        //HDOJ 5199 Gunner
 {
     //freopen ("B.in", "r", stdin);

     while (scanf ("%d%d", &n, &m) == )
     {
         memset (used, , sizeof (used));
         for (int i=; i<=n; ++i)    a[i] = read ();
         for (int i=; i<=m; ++i)    b[i] = read ();

         sort (a+, a++n);
         for (int i=; i<=m; ++i)
         {
             int x = upper_bound (a+, a++n, b[i]) - a;
             int y = lower_bound (a+, a++n, b[i]) - a;
             if (used[x])
             {
                 puts (""); continue;
             }
             used[x] = ;
             printf ("%d\n", x - y);
         }
     }

     return ;
 }

 #include <cstdio>
 #include <iostream>
 #include <cstring>
 #include <map>
 using namespace std;

 const int MAXN = 1e6 + ;
 const int INF = 0x3f3f3f3f;

 inline int read(void)
 {
     int x = , f = ;    char ch = getchar ();
     while (ch < '' || ch > '')    {if (ch == '-') f = -;    ch = getchar ();}
     while (ch >= '' && ch <= '')    {x = x *  + ch - '';    ch = getchar ();}
     return f * x;
 }
 int main(void)
 {
     //freopen ("B.in", "r", stdin);

     int n, m;
     while (scanf ("%d%d", &n, &m) == )
     {
         map<int, int> ma;    int x;
         while (n--)
         {
             x = read ();   ma[x]++;
         }
         map<int, int>::iterator it;
         while (m--)
         {
             x = read ();
             it = ma.find (x);
             if (it == ma.end ())
                 puts ("");
             else
             {
                 printf ("%d\n", it->second);
                 it->second = ;
             }
         }
     }

     return ;
 }

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