C++博客-purplest-随笔分类-枚举

poj 2909 Goldbach's Conjecture

purplest — Tue, 16 Aug 2011 16:41:00 GMT

用素数筛法筛一次，然后验算下就OK

#include <stdio.h>
#include <string.h>

int t[33000], prime[3000], p= 0;
int m, count;

void init()
{
    memset (t, 0, sizeof(t));
    for ( int i = 2 ; i < 33000 ; i++ )
    {
        if( !t[i] )
        {
            prime[p++]= i;
            for ( int j = i*2; j < 33000 ; j += i )
                t[j]= 1;
        }
    }
}

int main()
{
    init();
    while ( scanf("%d", &m), m )
    {
        count=0;
        int mid= m>>1;
        int i, j, a;
        for ( i = 0; prime[i] <= mid; i++ )
        {
            a= prime[i];
            if ( !t[m-a] )
                count++;
        }
        printf("%d\n", count);
    }
    return 0;
}

purplest 2011-08-17 00:41 发表评论

poj 1222 EXTENDED LIGHTS OUT

purplest — Wed, 10 Aug 2011 16:26:00 GMT

这题用的是暴力枚举第一排的情况，然后出解，听discuss里说能用高斯消去发，有空再试

#include <stdio.h>
#include <string.h>

int n;
int data[10][10], t[10][10], da[10][10];
int dir[4][2]={{1,0},{0,1},{-1,0},{0,-1}};

void turn(int i, int j)
{
    t[i][j]=!t[i][j];
    int x, y;
    for ( int k = 0; k < 4; k++ )
    {
        y=i+dir[k][0];
        x=j+dir[k][1];
        if ( 0 <= x && x < 6 && 0 <= y && y < 5) t[y][x]=!t[y][x];
    }
}
int work()
{
    int i, j;
    for ( i = 0; i < 5; i++ )
        for ( j = 0; j <6; j++ )
            t[i][j]=data[i][j];
    for ( j = 0; j < 6; j++ )
        if ( da[0][j] ) turn(0, j);
    for ( i = 1; i < 5; i++ )
    {
        for ( j = 0; j <6; j++ )
        {
            if (t[i-1][j])
            {
                turn(i, j);
                da[i][j]=1;
            }
        }
    }
    for ( i = 0; i < 5; i++ )
        for ( j = 0; j < 6; j++ )
            if ( t[i][j] ) return 0;
    return 1;
}
void print()
{
    for ( int i = 0; i < 5; i++ )
    {
        printf("%d", da[i][0]);
        for ( int j = 1; j < 6; j++ )
            printf(" %d", da[i][j]);
        putchar(10);
    }
}

int main()
{
    scanf("%d", &n);
    int m, i, j, k, num;
    for ( m = 1; m <= n; m++ )
    {
        for ( i = 0; i < 5 ; i++ )
            for ( j = 0; j < 6 ; j++ )
                scanf("%d", data[i]+j);
        printf("PUZZLE #%d\n", m);
        for ( k = 0; k < 64; k++ )
        {
            num= k;
            memset(da, 0, sizeof(da));
            for ( j = 0; j < 6 && num; j++ )
            {
                da[0][j]=num&1;
                num=num>>1;
            }
            if (1 == work())
                print();
        }
    }
    return 0;
}

purplest 2011-08-11 00:26 发表评论

poj 2200 A Card Trick

purplest — Fri, 05 Aug 2011 15:10:00 GMT

用STL中的next_permutation枚举出所有情况判断一下就OK

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
struct card
{
    string str;
    int v;
    char ch;
}data[5];
int n;

void init()
{
    int i;
    for ( i = 0 ; i < 5 ; i++ )
    {
        cin>>data[i].str;
        if ('2' <= data[i].str[0] && '9' >= data[i].str[0])
        {
            data[i].v= data[i].str[0]-'0';
            data[i].ch=data[i].str[1];
        }
        else if ('1' == data[i].str[0])
        {
            data[i].v=10;
            data[i].ch=data[i].str[2];
        }
        else if ( 'A' == data[i].str[0] )
        {
            data[i].v=1;
            data[i].ch=data[i].str[1];
        }
        else if ( 'J' == data[i].str[0] )
        {
            data[i].v=11;
            data[i].ch=data[i].str[1];
        }
        else if ('Q' == data[i].str[0])
        {
            data[i].v=12;
            data[i].ch=data[i].str[1];
        }
        else if ('K' == data[i].str[0])
        {
            data[i].v=13;
            data[i].ch=data[i].str[1];
        }
    }
}

bool cmp(card i, card j)
{
    if (i.v != j.v)
        return i.v < j.v;
    else
        return i.ch < j.ch;
}

int find()
{
    if (data[0].ch != data[1].ch)
        return 0;
    int i, min=data[2].v, k=2, t=data[1].v;
    for ( i = 3; i < 5; i++ )
    {
        if ( min > data[i].v )
        {
            min = data[i].v;
            k= i;
        }
    }
    if ( k == 2)
    {
        if ( data[3].v == data[4].v )
        {
            if ( data[3].ch > data[4].ch ) t+=3;
        }
        else
        {
            if (data[3].v > data[4].v) t+=3;
        }
    }
    if ( k == 3)
    {
        if ( data[2].v == data[4].v )
        {
            if ( data[2].ch > data[4].ch ) t+=3;
        }
        else
        {
            if (data[2].v > data[4].v) t+=3;
        }
    }
    if ( k == 4)
    {
        if ( data[2].v == data[3].v )
        {
            if ( data[2].ch > data[3].ch ) t+=3;
        }
        else
        {
            if (data[2].v > data[3].v) t+=3;
        }
    }
    t+=k-1;
    if ( t > 13) t-=13;
    if ( t == data[0].v ) return 1;
    else return 0;
}

void work()
{
    sort(data, data+5, cmp);
    do
    {
        if(find()) return;
    }
    while ( next_permutation(data, data+5, cmp));
}

int main()
{
    scanf("%d", &n);
    {
        int i, k;
        for ( k = 1 ; k <= n ; k++ )
        {
            init();
            work();
            printf("Problem %d:", k);
            for ( i = 0 ; i < 5 ; i++ )
                printf(" %s", data[i].str.c_str());
            putchar(10);
        }
    }
    return 0;
}

purplest 2011-08-05 23:10 发表评论