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 (≤10​^5​​). 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

题目大意

题目给定若干个整数，要求找到并输出不在给定序列中的最小的正整数。

解题思路

1. 采用打表法记录在最小和最大范围内出现的数字；
2. 从1开始遍历散列表，找到第一个散列表数值为0的数字时输出并跳出循环；
3. 返回零值。

代码

[code]#include<stdio.h>
#define maxn 100010
int arr[maxn];

int main(){
int i,N,a;
scanf("%d",&N);
while(N--){
scanf("%d",&a);
if(a>=0&&a<maxn){
arr[a]=1;
}
}
for(i=1;1;i++){
if(arr[i]==0){
printf("%d\n",i);
return 0;
}
}
}

运行结果