「CF440A」Forgotten Episode

2014年6月4日2,1200

Polycarpus adores TV series. Right now he is ready to finish watching a season of a popular sitcom “Graph Theory”. In total, the season has n episodes, numbered with integers from 1 to n.

Polycarpus watches episodes not one by one but in a random order. He has already watched all the episodes except for one. Which episode has Polycaprus forgotten to watch?

Input

The first line of the input contains integer n (2 ≤ n ≤ 100000) — the number of episodes in a season. Assume that the episodes are numbered by integers from 1 to n.

The second line contains n - 1 integer a1, a2, …, an (1 ≤ ai ≤ n) — the numbers of episodes that Polycarpus has watched. All values ofai are distinct.

Output

Print the number of the episode that Polycarpus hasn’t watched.

Sample test(s)

input

10
3 8 10 1 7 9 6 5 2

1 2	10 3 8 10 1 7 9 6 5 2

output

4

题解

不解释

#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
inline int read()
{
    int x=0,f=1;char ch=getchar();
    while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
    while(ch>='0'&&ch<='9'){x*=10;x+=ch-'0';ch=getchar();}
    return x*f;
}
int n;
bool used[100005];
int main()
{
    n=read();
    int x;
    for(int i=1;i<n;i++)
        x=read(),used[x]=1;
    for(int i=1;i<=n;i++)
        if(!used[i])printf("%d",i);
    return 0;
}

#include<iostream>

#include<cstdio>

#include<cstring>

using namespace std;

inline int read()

{

int x=0,f=1;char ch=getchar();

while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}

while(ch>='0'&&ch<='9'){x*=10;x+=ch-'0';ch=getchar();}

return x*f;

}

int n;

bool used[100005];

int main()

{

n=read();

int x;

for(int i=1;i<n;i++)

x=read(),used[x]=1;

for(int i=1;i<=n;i++)

if(!used[i])printf("%d",i);

return 0;

}

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「CF440A」Forgotten Episode

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