pku 2085 纯粹找规律

//AC Code
#include <iostream>
#define Swap(x,y) {int temp = x;x = y;y = temp;}
#define MAX 50001
int map[MAX];
bool hash[MAX];
int main()
{
int i, j, k, n, v;
while(scanf("%d%d", &n, &v) && n != -1)
{
memset(hash, false, sizeof(bool)*(n+1));
i = 2;
while((i-1)*(i+2)/2 < v)
i++;
for(j = 1; j <= n-i-1;++j)
{
hash[j] = true;
printf("%d ", j);
}
k = n-i-1 + v - (i-2)*(i+1)/2;
printf("%d %d ", k, n);
hash[k] = hash
= true;

for(j = n; j >= n-i; --j)
if(!hash[j])
printf("%d ", j);
printf("/n");
}
return 0;
}
//O(n)

#include <iostream>
#include <algorithm>
using namespace std;
#define MAX 50001
int map[MAX];
void print(int& v)
{
printf("%d ", v);
}
int calculate(int n)
{
int cnt = 0;
for(int i = 1; i <= n-1; ++i)
for(int j = i+1; j <= n; ++j)
if(map[i] > map[j])
cnt++;
return cnt;
}
int main()
{
int n, v;
while(scanf("%d%d", &n, &v) && !(n == -1 && v == -1))
{
for(int i = 1; i <= n; ++i)
map[i] = i;
while(next_permutation(map+1, map+n+1))
{
if(calculate(n) == v)
{
for_each(map+1, map+n+1, print);
printf("/n");
break;
}
}
}
return 0;
}
O(n^4)

#include <iostream>
#include <algorithm>
using namespace std;
#define MAX 50001
int map[MAX];
void next(int n)
{
int i;
for(i = n; i >= 1 && map[i-1] > map[i]; i--)
;
int low = i, high = n;
while(low <= high)
{
int mid = (low+high) >> 1;
if(map[mid] < map[i-1])
high = mid-1;
else
low = mid+1;
}
std::iter_swap(map+i-1, map+high);
}
int main()
{
int n, v;
while(scanf("%d%d", &n, &v) && !(n == -1 && v == -1))
{
for(int i = 1; i <= n; ++i)
map[i] = i;
for(int i = 1; i <= v; ++i)
next(n);
for(int i = 1; i <= n; ++i)
printf("%d ", map[i]);
printf("/n");

}
return 0;
}
//O(n^2*logn)

#include <stdio.h>
#define Swap(x,y) {int temp = x;x = y;y = temp;}
#define MAX 50001
int map[MAX];
int main()
{
int i, n, v;
int x, y;
while(scanf("%d%d", &n, &v) && n != -1)
{
for(i = 1; i <= n; ++i)
map[i] = i;
x = n-1, y = n;
for(i = 1; i <= v; ++i)
{
if(x < y)
{
Swap(map[x],map[y]);
y--;
}
else
{
x--;
y = n;
Swap(map[x], map[y]);
y--;
}
}
for(i = 1; i <= n; ++i)
printf("%d ", map[i]);
printf("/n");
}
return 0;
}
//O(v) = O(n^2) result: 命中注定TLE