A. Adjacent Replacements
time limit per test
1 second
memory limit per test
256 megabytes
input
standard input
output
standard output
Mishka got an integer array aa of length nn as a birthday present (what a surprise!).
Mishka doesn't like this present and wants to change it somehow. He has invented an algorithm and called it "Mishka's Adjacent Replacements Algorithm". This algorithm can be represented as a sequence of steps:
- Replace each occurrence of 11 in the array aa with 22;
- Replace each occurrence of 22 in the array aa with 11;
- Replace each occurrence of 33 in the array aa with 44;
- Replace each occurrence of 44 in the array aa with 33;
- Replace each occurrence of 55 in the array aa with 66;
- Replace each occurrence of 66 in the array aa with 55;
- ……
- Replace each occurrence of 109−1109−1 in the array aa with 109109;
- Replace each occurrence of 109109 in the array aa with 109−1109−1.
Note that the dots in the middle of this algorithm mean that Mishka applies these replacements for each pair of adjacent integers (2i−1,2i2i−1,2i) for each i∈{1,2,…,5⋅108}i∈{1,2,…,5⋅108} as described above.
For example, for the array a=[1,2,4,5,10]a=[1,2,4,5,10], the following sequence of arrays represents the algorithm:
[1,2,4,5,10][1,2,4,5,10] →→ (replace all occurrences of 11 with 22) →→ [2,2,4,5,10][2,2,4,5,10] →→ (replace all occurrences of 22 with 11) →→ [1,1,4,5,10][1,1,4,5,10] →→ (replace all occurrences of 33 with 44) →→ [1,1,4,5,10][1,1,4,5,10] →→ (replace all occurrences of 44 with 33) →→ [1,1,3,5,10][1,1,3,5,10] →→ (replace all occurrences of 55 with 66) →→ [1,1,3,6,10][1,1,3,6,10] →→ (replace all occurrences of 66 with 55) →→ [1,1,3,5,10][1,1,3,5,10] →→ …… →→ [1,1,3,5,10][1,1,3,5,10] →→ (replace all occurrences of 1010 with 99) →→ [1,1,3,5,9][1,1,3,5,9]. The later steps of the algorithm do not change the array.
Mishka is very lazy and he doesn't want to apply these changes by himself. But he is very interested in their result. Help him find it.
Input
The first line of the input contains one integer number nn (1≤n≤10001≤n≤1000) — the number of elements in Mishka's birthday present (surprisingly, an array).
The second line of the input contains nn integers a1,a2,…,ana1,a2,…,an (1≤ai≤1091≤ai≤109) — the elements of the array.
Output
Print nn integers — b1,b2,…,bnb1,b2,…,bn, where bibi is the final value of the ii-th element of the array after applying "Mishka's Adjacent Replacements Algorithm" to the array aa. Note that you cannot change the order of elements in the array.
Examples
input
Copy
5
1 2 4 5 10
output
Copy
1 1 3 5 9
input
Copy
10
10000 10 50605065 1 5 89 5 999999999 60506056 1000000000
output
Copy
9999 9 50605065 1 5 89 5 999999999 60506055 999999999
Note
The first example is described in the problem statement.
题目理解起来很简单，即奇数不变，偶数减一
错误代码：
#include<stdio.h>
main() {
int a[2500];
int n;
while(scanf("%d",&n)!=EOF&&n<=1000&&n>=1) {
for(int i=0; i<n; i++) {
scanf("%d",&a[i]);
if(a[i]%2==0)
a[i]=a[i]-1;
}
for(int i=0; i<n; i++)
if(i!=n-1)
printf("%d ",a[i]);
else printf("%d",a[i]);
}
}错因：Time limit exceeded on test 3
这种错误在初学者身上经常发现，一般常见于for循环语句
以下是某位大神的代码：
#include <cstdio>
int a, n;
int main()
{
scanf("%d", &n);
for(int i = 0; i < n; ++i)
{
scanf("%d", &a);
a -= (a & 1) ^ 1;
printf("%d ", a);
}
return 0;
}
此处灵活用到了&与^符号的应用，&相同则为0，否则为1，而^运算，有0则为0；