PAT 甲级 1144 The Missing Number (20 分)(简单,最后一个测试点没过由于开的数组没必要大于N)...
1144 The Missing Number (20 分)
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
题意:
给你一个序列,让你找一个数x,x是不在这个序列里的最小正整数。
题解:
做此题的时候,最后一个测试点老是段错误,仔细查看下数据范围int,如果开一个int范围大小的数组判断,显然不可能,那么就猜下测试数据的范围。最后一个测试点没过由于开的数组没必要大于N。因为总共不会超过100000的数,所以在100002前一定会出现一个最小数没有出现。
AC代码:
#include<bits/stdc++.h> using namespace std; int n; int a[100010]; int main(){ cin>>n; for(int i=1;i<=n;i++){ int x; cin>>x; if(x>0 && x<=100002){ //总共不会超过100000的数,所以在100002前一定会出现一个最小数没有出现 a[x]=1; } } for(int i=1;i<=100002;i++){ if(!a[i]){ cout<<i; break; } } return 0; }