Permutation Recovery
Time Limit: 10000/4000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 451 Accepted Submission(s): 312
Problem Description
Professor
Permula gave a number of permutations of the n integers 1, 2, ..., n to
her students. For each integer i (1 <= i <= n), she asks the
students to write down the number of integers greater than i that
appears before i in the given permutation. This number is denoted ai.
For example, if n = 8 and the permutation is 2,7,3,5,4,1,8,6, then a1 = 5
because there are 5 numbers (2, 7, 3, 5, 4) greater than 1 appearing
before it. Similarly, a4 = 2 because there are 2 numbers (7, 5) greater
than 4 appearing before it.
Permula gave a number of permutations of the n integers 1, 2, ..., n to
her students. For each integer i (1 <= i <= n), she asks the
students to write down the number of integers greater than i that
appears before i in the given permutation. This number is denoted ai.
For example, if n = 8 and the permutation is 2,7,3,5,4,1,8,6, then a1 = 5
because there are 5 numbers (2, 7, 3, 5, 4) greater than 1 appearing
before it. Similarly, a4 = 2 because there are 2 numbers (7, 5) greater
than 4 appearing before it.
John, one of the students in the
class, is studying for the final exams now. He found out that he has
lost the assignment questions. He only has the answers (the ai's) but
not the original permutation. Can you help him determine the original
permutation, so he can review how to obtain the answers?
Input
The
input consists of a number of test cases. Each test case starts with a
line containing the integer n (n <= 500). The next n lines give the
values of a1, ..., an. The input ends with n = 0.
input consists of a number of test cases. Each test case starts with a
line containing the integer n (n <= 500). The next n lines give the
values of a1, ..., an. The input ends with n = 0.
Output
For
each test case, print a line specifying the original permutation.
Adjacent elements of a permutation should be separated by a comma. Note
that some cases may require you to print lines containing more than 80
characters.
each test case, print a line specifying the original permutation.
Adjacent elements of a permutation should be separated by a comma. Note
that some cases may require you to print lines containing more than 80
characters.
Sample Input
8
5
0
1
2
1
2
0
0
10
9
8
7
6
5
4
3
2
1
0
0
5
0
1
2
1
2
0
0
10
9
8
7
6
5
4
3
2
1
0
0
Sample Output
2,7,3,5,4,1,8,6
10,9,8,7,6,5,4,3,2,1
10,9,8,7,6,5,4,3,2,1
题解：这个题就是给你了逆序数，让你求出原排列；我的思路是从1到N，一次放在数组中，因为i之前的肯定比i小，所以如果a[i]=0逆序数加一；证明a[i]还没放，没放肯定比i大喽；
代码：
#include<stdio.h>
#include<string.h>
const int MAXN=;
int main(){
int N,x;
int ans[MAXN];
while(~scanf("%d",&N),N){
memset(ans,,sizeof(ans));
for(int i=;i<=N;i++){
scanf("%d",&x);
int tot=;
for(int j=;j<=N;j++){
if(ans[j])continue;
if(tot==x){
ans[j]=i;break;
}
if(!ans[j])tot++;
}
}
for(int i=;i<=N;i++){
if(i-)printf(",");
printf("%d",ans[i]);
}
puts("");
}
return ;
}