7.14被虐记

要仔细看题，不然PE和各种莫名其妙的WA就来了！今天开始继续写博客！

http://acm.hdu.edu.cn/showproblem.php?pid=3625

/*Accepted 3625 0MS 248K 818B C++ Yu */

#include<cstdio>
#include<cstring>

#define LL __int64
LL dp[21][21];
LL sum;
double ans[21][21], p[21][21];

void init()
{
    memset( dp, 0, sizeof dp);
    memset( ans, 0, sizeof ans);
    memset( p, 0, sizeof p);
    dp[1][1] = 1;
    sum = 1;
}

void cal()
{
    for( int i = 2; i <= 20; i ++)
    {
        dp[i][i] = 1;
        sum *= i; //N!
        for( int j = 1; j < i; j ++)
        {
            dp[i][j] = (i - 1) * dp[i - 1][j] + dp[i - 1][j - 1];
            ans[i][j] = ( 1.0 * ((i - 1) * dp[i - 1][j])) / sum;
        }
    }
    for( int i = 2; i <= 20; i ++)
    {
        for( int j = 1; j < i; j ++)
        {
            p[i][j] = ans[i][j];
            p[i][j] += p[i][j - 1];
        }
    }
}

int main()
{
    int T;
    int n, k;
    init();
    cal();
    scanf( "%d", &T);
    while( T --)
    {
        scanf( "%d%d", &n, &k);
        printf( "%.4lf\n", p[n][k]);
    }
    return 0;
}

http://acm.hdu.edu.cn/showproblem.php?pid=3626

/*Accepted 3626 0MS 244K 970 B C++ */

#include<cstdio>
#include<cstring>
#include<cstdlib>

const int MAXN = 1005;
typedef struct cood
{
    int x, y;
}C;

C c[MAXN], s[MAXN];
int n;

int cmp( const void *_p, const void *_q)
{
    C *p = (C *)_p;
    C *q = (C *)_q;
    if( p->x == q->x)
        return p->y - q->y;
    return p->x - q->x;
}

void input()
{
    for( int i = 0; i < n; i ++) {
        scanf( "%d%d", &c[i].x, &c[i].y);
        s[i].x = c[i].x, s[i].y = c[i].y;
    }
    qsort( s, n, sizeof s[0], cmp);
}

void output()
{
    bool flag = false;
    for( int i = 0; i < n; i ++){
        flag = false;
        for( int j = 0; j < n; j ++)
        {
            if( c[i].x < s[j].x && c[i].y < s[j].y )
            {
                printf( "%d %d\n", s[j].x, s[j].y);
                flag = true;
                break;
            }
        }
        if( !flag) printf( "-1 -1\n");
    }
}

int main()
{
    int cas = 0;
    while( scanf( "%d", &n) == 1)
    {
        if( 0 == n) break;
        if( cas ++) printf( "\n");
        printf( "Case %d:\n", cas);
        input();
        output();
    }
    return 0;
}

http://acm.hdu.edu.cn/showproblem.php?pid=3631

/*Accepted 3631 234MS 592K 1393 B C++ */
#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;

const int MAXN = 305;
const int inf = 0x3f3f3f3f;
int map[MAXN][MAXN];
bool vis[MAXN];
int n, m, q;

void init()
{
    memset( vis, false, sizeof vis);
    for( int i = 0; i < n; i ++){
        for( int j = 0; j < n; j ++)
        {
            map[i][j] = inf;
        }
        map[i][i] = 0;
    }
}

void floyd( int k)
{
    for( int i = 0; i < n; i ++)
        for( int j = 0; j < n; j ++)
        {
            map[i][j] = min( map[i][j], map[i][k] + map[k][j]);
        }
}

void input()
{
    int a, b, c;
    while( m --)
    {
        scanf( "%d%d%d", &a, &b, &c);
        map[a][b] = min( c, map[a][b]);
    }
}

void operation()
{
    int op, x, y;
    while( q --)
    {
        scanf( "%d", &op);
        if( 0 == op) {
            scanf( "%d", &x);
            if(!vis[x]){
                vis[x] = true;
                floyd(x);
            }
            else {
                printf( "ERROR! At point %d\n", x);
            }
        }
        if( 1 == op) {
            scanf( "%d%d", &x, &y);
            if( !vis[x] || !vis[y]){
                printf( "ERROR! At path %d to %d\n", x, y);
            }
            else {
                if( map[x][y] != inf)
                    printf( "%d\n", map[x][y]);
                else
                    printf( "No such path\n");
            }
        }
    }
}

int main()
{
    int cas = 0;
    while( scanf("%d%d%d", &n, &m, &q) != EOF)
    {
        if( 0 == n && 0 == m && 0 == q) break;
        if( cas ++) printf( "\n");
        printf( "Case %d:\n", cas);
        init();
        input();
        operation();
    }
    return 0;
}