HDU 1104 Remainder

BFS。

#include<cstdio>
#include<cstring>
#include<queue>
#include<string>
#include<algorithm>
#include<map>
#include<iostream>
using namespace std;

int n,m,k;
struct Node
{
    int nowN;
    int tot;
    string op;
    Node(int t,int nown,string o)
    {
        tot=t;
        nowN=nown;
        op=o;
    }
};
queue<Node>Q;
map<int,int>t;

int MOD(int a,int b)
{
    if(a>=0) return a%b;
    if(abs(a)%b==0) return 0;
    return (a+b*(abs(a)/b+1));
}

void BFS()
{
    int flag=0;
    while(!Q.empty()) Q.pop();
    t.clear();
    Node s(0,MOD(n,m*k),"");
    Q.push(s);
    while(!Q.empty())
    {
        Node head=Q.front(); Q.pop();

        if(MOD(n+1,k)==MOD(head.nowN,k))
        {
            flag=1;
            printf("%d\n",head.tot);
            cout<<head.op<<endl;
            break;
        }
        if(t[MOD(head.nowN+m,m*k)]==0)
        {
            t[MOD(head.nowN+m,m*k)]=1;
            Node s1(head.tot+1,MOD(head.nowN+m,m*k),head.op+"+");
            Q.push(s1);
        }
        if(t[MOD(head.nowN-m,m*k)]==0)
        {
            t[MOD(head.nowN-m,m*k)]=1;
            Node s2(head.tot+1,MOD(head.nowN-m,m*k),head.op+"-");
            Q.push(s2);
        }
        if(t[MOD(head.nowN*m,m*k)]==0)
        {
            t[MOD(head.nowN*m,m*k)]=1;
            Node s3(head.tot+1,MOD(head.nowN*m,m*k),head.op+"*");
            Q.push(s3);
        }
        if(t[MOD(MOD(head.nowN,m),m*k)]==0)
        {
            t[MOD(MOD(head.nowN,m),m*k)]=1;
            Node s4(head.tot+1,MOD(MOD(head.nowN,m),m*k),head.op+"%");
            Q.push(s4);
        }
    }
    if(!flag) printf("0\n");
}

int main()
{
    while(~scanf("%d%d%d",&n,&k,&m))
    {
        if(!n&&!m&&!k) break;
        BFS();
    }
    return 0;
}