能不能公布一下解题的算法呢？让新手也有一个提高自己的机会呢？谢谢了

#include<fstream>
#include <iostream>

using namespace std;

void solve(int n, int k)
{
int i;
bool is_ok = false;
for(i=0; i< (n/2 +1);i++)
{
if(i*(n-1) == k)
is_ok = true;
}

if(is_ok)
{
cout << "YES"<<endl;
}else{
cout << "NO"<<endl;
}
}
int main()
{
int k;
int n;
ifstream fin("input_5.txt" );
if(! fin)
cout <<"error in open corpus.txt";
while(! fin.eof())
{
fin >> n;
fin >>k;
solve(n, k);
}
fin.close();
}

#include<fstream>
#include <iostream>

using namespace std;

int a[500];
bool isok;
int cur_n;
long cur_k;

void calculate(int total)
{
long sum = 0;
int i, j;

for (i=0; i < total - 1; i++)
{
for(j = i+1; j< total; j++)
sum += a[i]*a[j];
}
for (i=0; i < total; i++)
cout << a[i]<<" ";
cout << endl;
if(sum == cur_k)
{
isok = true;
}
}

void fillGroup(int n, int group_id)
{
int i;
for(i=1; i<= n/2;i++)
{
a[group_id] = i;
a[group_id+1] = n -i;
calculate(group_id+2);
if(isok)
return;
if(n>i)
{
fillGroup(n-i, group_id+1);
}
}
}

void solve(int n, long k)
{
isok = false;
fillGroup(n, 0);
if(isok)
{
cout << "YES"<<endl;
}else{
cout << "NO"<<endl;
}
}

int main()
{
ifstream fin("input_5.txt" );
if(! fin)
{
cout <<"error in open corpus.txt";
exit(1);
}
while(! fin.eof())
{
cur_n = 0;
cur_k = 0;
fin >> cur_n;
fin >>cur_k;
if(cur_k == 0)
{
cout <<"YES"<<endl;
continue;
}
solve(cur_n, cur_k);
}
fin.close();
}

3楼和4楼是一连在一起的,长度限制,所以分两次发!

2楼程序有问题～～～

Eli261的程序可借鉴一下。

总比赛场数可以這樣算:
long sum = 0;
for(int i = 0; i < total; ++i)
sum += a[i] * (n - a[i]);
sum /= 2;

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#define MAX 500

typedef struct Lnode
{
int data;
bool result;
struct Lnode* next;
} Lnode;

Lnode note[MAX];
Lnode* head[MAX];

bool fun( int n, int k )
{
Lnode* p = head[n - 1] -> next;
bool h;
int tmp, i;
while ( p != NULL && p -> data != k )
{
p = p -> next;
}
if ( p != NULL )
{
return p -> result;
}
for ( i = 1, h = false; i <= ( n >> 1 ); ++i )
{
tmp = k - i * ( n - i );
if ( tmp == 0 || ( tmp > 0 && fun( n - i, tmp ) ) )
{
h = true;
break;
}
}
p = ( Lnode* )malloc( sizeof( Lnode ) );
p -> data = k;
p -> result = h;
p -> next = head[n - 1] -> next;
head[n - 1] -> next = p;
return h;
}

void del( Lnode* L )
{
Lnode* p = L -> next;
Lnode* tmp;
while ( p != NULL )
{
tmp = p;
p = p -> next;
free( tmp );
}
}

int main( void )
{
int n, k, i;
for ( i = 0; i < MAX; ++i )
{
head[i] = &( note[i] );
head[i] -> next = NULL;
}
scanf( "%d%d", &n, &k );
k == 0 ? k = n - 1 : NULL;
clock_t t = clock();
printf( "%s\n", fun( n, k ) == true ? "YES" : "NO" );
for ( i = 0; i < MAX; ++i )
{
del( head[i] );
}
t = clock() - t;
printf( "Time = %d\n", t );
system( "pause" );
return 0;
}
注:文件打开和读取没有写,可以自己改

#include <stdio.h>

int stepby(int n)
{
if(n == 1)
{
return 1;
}else
{
return n*stepby(n-1);
}
}

static
int check(int N, int K)
{
int i, j, flag = -1;

if(N>500 || N<0 || K<0)
return -1;
if(!K)
return 0;
for(i = 2;i<=N;i++)
{
if((N-i+1)*stepby(i -1) == K)
flag = 0;
}
return flag;
}
int main()
{
FILE* file, *fo;
int N,K;

file = fopen("in.txt","r");
fo = fopen("out.txt","w");

while(fscanf(file, "%d %d", &N, &K) >0)
{
if(!check(N, K))
{
fprintf(fo, "YES\n");
}else
{
fprintf(fo, "NO\n");
}
}

if(file)
fclose(file);
if(fo)
fclose(fo);
return 0;
}

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