PAT_A1144#The Missing Number

Source:

PAT A1144 The Missing Number (20 分)

Description:

Given N integers, you are supposed to find the smallest positive integer that is NOT in the given list.

Input Specification:

Each input file contains one test case. For each case, the first line gives a positive integer N (≤). Then N integers are given in the next line, separated by spaces. All the numbers are in the range of int.

Output Specification:

Print in a line the smallest positive integer that is missing from the input list.

Sample Input:

10
5 -25 9 6 1 3 4 2 5 17

Sample Output:

7

Keys:

• 散列（Hash）

Code:

 /*
 Data: 2019-05-23 19:50:36
 Problem: PAT_A1144#The Missing Number
 AC: 05:24

 题目大意：
 给定N（<=1e5）个整数（int范围内），找出不在表中的最小正数；
 */

 #include<cstdio>
 #include<map>

 int main()
 {
 #ifdef    ONLINE_JUDGE
 #else
     freopen("Test.txt", "r", stdin);
 #endif

     int n,x;
     std::map<int,int> mp;
     scanf("%d", &n);
     for(int i=; i<n; i++)
     {
         scanf("%d", &x);
         mp[x]=;
     }
     for(int i=; i<1e9; i++)
     {
         if(mp[i]==)
         {
             printf("%d\n", i);
             break;
         }
     }

     return ;
 }