Remainder

#include<stdio.h>
#include<iostream>
#include<string>
#include<cstring>
#include<queue>
 using namespace std;
 struct cc
{
    int n,m;
};
 string op[1005];
 int step[1005];
 int vis[1005],ans,k;
 int main()
{
    int n,m,ok,flag;
    while(scanf("%d%d%d",&n,&k,&m)==3)
    {
        ok=0;
        if(!n&&!m&&!k)break;
        memset(step,0,sizeof(step));
        memset(vis,0,sizeof(vis));
        ans=(n+1+1000*k)%k;
        for(int i=0;i<=1001;i++)
            op[i].clear();
        queue <cc> q;
        cc c;
        c.m=(n+1000*m)%m;//注意n=-1和n=-1+10(k)做%运算结果不一样，所以事先存n%m;当以后遇到%时c.n=c.m%m；
        c.n=(n+1000*k)%k;
        q.push(c);
        vis[c.n]=1;
        while(!q.empty())
        {
            cc temp=q.front();
            q.pop();
            for(int i=0;i<4;i++)
            {
                cc u=temp;
                switch(i)
                {
                case 0:u.n=(u.n+m+1000*k)%k;break;
                case 1:u.n=(u.n-m+1000*k)%k;break;
                case 2:u.n=(u.n*m+1000*k)%k;u.m=0;break;//u.n*mºó£¬u.n%m==0£»ÒÔºóÓöµ½%ÔËËãºóu.n==0!=u.m%m;
                case 3:u.n=(u.m+1000*k)%k;break;
                }
                if(!vis[u.n])
                {
                    step[u.n]=step[temp.n]+1;
                    vis[u.n]=1;
                    switch(i)
                    {
                    case 0:op[u.n]=op[temp.n]+'+';break;
                    case 1:op[u.n]=op[temp.n]+'-';break;
                    case 2:op[u.n]=op[temp.n]+'*';break;
                    case 3:op[u.n]=op[temp.n]+'%';break;
                    }
                    q.push(u);
                    if(u.n==ans){ok=1;flag=u.n;break;}   
                }
              
            }
              if(ok)break;   
        }
        if(!ok)printf("0\n");
        else
        {
            int t=0;
            printf("%d\n",step[flag]);
            cout<<op[flag]<<endl;
        }
    }
}

不容易啊，这年头，抄个代码也要找好多才能找到一个真正可以AC的

http://www.cnblogs.com/sook/archive/2011/03/18/1988307.html

我的WA的DFS，果断超时

#include <iostream>
using namespace std;

int n, k, m, count, mmin;
bool flag;
const int N = 1010;
bool visited[N];
char path[N];
char finalP[N];
char op[5] = "+-*%";

void getValue(int arr[], int value)
{
    arr[0] = (value + m) % k;
    arr[1] = (value - m) % k;
    arr[2] = (value * m) % k;
    arr[3] = (value % m) % k;
}

void dfs(int num, int count)
{
    if(num == (n + 1) % k && count < mmin)
    {
        mmin = count;
        for(int i = 0; i < count; ++i)
            finalP[i] = path[i];
        flag = true;
    }
    int arr[4];
    getValue(arr, num);
    for(int i = 0; i < 4; ++i)
    {
        if(visited[arr[i]] == false)
        {
            visited[arr[i]] = true;
            path[count++] = op[i];
            dfs(arr[i], count);
            count--;
            visited[arr[i]] = false;
        }
    }
}

int main()
{
    while(cin >> n >> k >> m)
    {
        if( n == 0 && k == 0 && m == 0)
            break;
        ::count = 0;
        ::mmin = 1 << 30;
        visited[n] = true;
        flag = false;
        dfs(n, 0);    
        if(flag == false)
            cout << 0 << endl;    
        else
        {
            cout << ::mmin << endl;
            for(int i = 0; i < :: mmin; ++i)
                cout << finalP[i];
            cout << endl;
        }
    }
    return 0;
}

我的WA的BFS，果断超内存，泪奔。。。

#include <iostream>
#include <queue>
using namespace std;

int n, k, m;
const int N = 1010;
char op[5] = "+-*%";
struct Node{
    int num;
    char op[N];
    bool v[N];
    int count;
};
void getValue(int arr[], int value)
{
    arr[0] = (value + m) % k;
    arr[1] = (value - m) % k;
    arr[2] = (value * m) % k;
    arr[3] = (value % m) % k;
}

void bfs()
{
    bool flag = false;
    queue<Node> q;
    Node a, b;
    a.num = n;
    for(int i = 0; i < k; ++i)
    {
        a.v[i] = false;
        a.op[i] = ' ';
    }
    a.v[n] = true;
    a.count = 0;
    q.push(a);
    int arr[4];
    while(!q.empty())
    {
        a = q.front();
        q.pop();
        if(a.num == (n + 1) % k)
        {
            flag = true;
            while(!q.empty())
                q.pop();    

            cout << a.count << endl;
            for(int i = 0; i < a.count; ++i)
                cout << a.op[i];
            cout << endl;
        }
        getValue(arr, a.num);
        for(int i = 0; i < 4; ++i)
        {
            if(a.v[arr[i]] == false)
            {
                b.num = arr[i];
                for(int i = 0; i < k; ++i)
                {
                    b.op[i] = a.op[i];
                    b.v[i] = a.v[i];
                }
                b.v[arr[i]] = true;
                b.op[a.count] = op[i];
                b.count = a.count + 1;
                q.push(b);
            }
        }
    }
    if(!flag)
        cout << 0 << endl;
}    
int main()
{
    while(cin >> n >> k >> m)
    {
        if( n == 0 && k == 0 && m == 0)
            break;
        bfs();        
    }
    return 0;
}