题目链接: 点击打开链接
宽度搜索 + 同余定理 + 记录路径
#include<iostream>
#include<queue>
#include<cstdio>
#include<algorithm>
#include<cstring>
#include<cmath>
#include<vector>
using namespace std;
const int MAXN = 1e6 + 5;
int N;
int pre[MAXN], val[MAXN];//pre , val 是用来记录路径
void print(int x)
{
if(pre[x] != -1)
{
print(pre[x]);
}
cout << val[x];
}
void bfs()
{
queue<int> p;
p.push(1);
pre[1] = -1;
val[1] = 1;
while(!p.empty())
{
int x = p.front();
p.pop();
int x1 = x*10, x2 = x1+1;
x1 %= N;
x2 %= N;
if(pre[x1] == 0)// 用同余剪枝,大大降低了程序的运行时间
{
pre[x1] = x;
val[x1] = 0;
p.push(x1);
}
if(pre[x2] == 0)
{
pre[x2] = x;
val[x2] = 1;
p.push(x2);
}
if(x1 == 0)
{
print(x1);
return ;
}
if(x2 == 0)
{
print(x2);
return ;
}
}
}
int main()
{
cin >> N;
if(N == 1)
cout << '1' << endl;
else
bfs();
return 0;
}