2017 ACM-ICPC 南宁区比赛 Minimum Distance in a Star Graph
2017-09-25 19:58:04
writer:pprp
题意看上去很难很难,但是耐心看看还是能看懂的,给你n位数字
你可以交换第一位和之后的某一位,问你采用最少的步数可以交换成目标
有五组数据
用BFS进行搜索,并进行剪枝,已经搜索过的点不再搜索
#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <string>
#include <set>
#include <queue>
using namespace std;
string sa, sb;
int n;
struct node
{
string str;
int times;
node()
{
str = "";
times = 0;
}
};
int bfs()
{
queue<node> q;
set<string> ss;
node now , nex;
now.str = sa;
q.push(now);
ss.insert(now.str);
while(!q.empty())
{
now = q.front();
q.pop();
if(now.str == sb)
return now.times;
for(int i = 1; i < n;i++)
{
nex.str = now.str;
nex.times = now.times+1;
nex.str[i] = now.str[0];
nex.str[0] = now.str[i];
if(ss.count(nex.str) == 0)
{
ss.insert(nex.str);
q.push(nex);
}
else
continue;
}
}
}
int main()
{
cin >> n;
for(int i = 0 ; i < 5 ;i++)
{
cin >> sa >> sb;
cout << bfs() << endl;
}
return 0;
}
现阶段掌握搜索还不是太好,希望以后可以尽快掌握
代码改变世界