<挑战程序设计竞赛> poj 3320 Jessica's Reading Problem 双指针

地址 http://poj.org/problem?id=3320

解答

使用双指针 在指针范围内是否达到要求

若不足要求则从右进行拓展  若满足要求则从左缩减区域

代码如下  正确性调整了几次 然后被输入卡TLE卡了很久都没意识到.........

 #include <iostream>
 #include <map>
 #include <set>
 #include <algorithm>
 #include <assert.h>
 #include <stdio.h>

 using namespace std;

 int n, m;

 const int MAX_N = ;

 int v[MAX_N];

 set<int> setint;

 int minLen = ;

 int main()
 {
     cin >> n;

     for (int i = ; i < n; i++) {
         //cin >> v[i];
         scanf("%d",&v[i]);
         setint.insert(v[i]);
     }

     int total = setint.size();

     int l = ; int r = ;
     map<int, int> mapcover;
     mapcover[v[l]]++;
     int count = ;

     while() {
         while (count < total) {
             r++;
             if (r >= n) {
                 printf("%d\n", minLen);
                 return ;
             }
             mapcover[v[r]]++;
             if (mapcover[v[r]] == ) {
                 //说明添加了一个新类型
                 count++;
             }
         }

         if (count < total) {
             break;
         }

         minLen = min(minLen, r - l + );

         //尝试缩小整个范围 从左端减少
         mapcover[v[l]]--;
         if (mapcover[v[l]] == ) {
             //说明减少了一个种类
             count--;
         }
         l++;
     }

     printf("%d\n", minLen);
     return ;
 }

ac code 1

 #include <iostream>
 #include <map>
 #include <set>
 #include <algorithm>
 #include <assert.h>
 #include <stdio.h>

 using namespace std;

 int n, m;

 const int MAX_N = ;

 int v[MAX_N];

 set<int> setint;

 int minLen = ;

 int main()
 {
     cin >> n;

     for (int i = ; i < n; i++) {
         scanf("%d",&v[i]);
         setint.insert(v[i]);
     }

     int total = setint.size();

     int l = ; int r = ;
     map<int, int> mapcover;
     mapcover[v[l]]++;
     int count = ;
     while () {
         if (count < total) {
             r++;
             if (r >= n) break;
             mapcover[v[r]]++;
             //添加了一个新元素 那么元素种类计数+1
             if (mapcover[v[r]] == ) count++;

         }
         else if(count == total) {
             minLen = min(minLen, r - l + );
             mapcover[v[l]]--;
             if (mapcover[v[l]] == ) {
                 count--;
             }
             l++;
             if (l >= n) break;
             if (l > r) {
                 r = l;
             }
         }
         else {
             assert();
         }

     }

     printf("%d\n",minLen);

     return ;
 }

ac code 2