2017 ACM-ICPC 亚洲区（南宁赛区）网络赛 J.Minimum Distance in a Star Graph

题目链接：Minimum Distance in a Star Graph
思路：模拟，因为只能把后面的和第一个交换，所以当第一个不在其应在的位置时，把它放到应在的位置；当第一个已经在它应在的位置时，去后面一个不在正确位置的点和第一个交换……直到字符串完全匹配。

#include <iostream>#include <cstdio>#include <fstream>#include <algorithm>#include <cmath>#include <deque>#include <vector>#include <queue>#include <string>#include <cstring>#include <map>#include <stack>#include <set>#define Max(a,b) a>b?a:b#define Min(a,b) a>b?b:a#define mem(a,b) memset(a,b,sizeof(a))using namespace std;typedef long long ll;int dir[4][2]= {{1,0},{-1,0},{0,1},{0,-1}};const double eps = 1e-6;const double Pi = acos(-1.0);const int INF=0x3f3f3f3f;int before[10];int after[10];map<int,int> mp;map<int,int> mp2;int n;bool check(){    for(int i = 1; i <= n; i++){        if(before[i] != after[i]) return true;    }    return false;}int main(){    int a,b;    while(~scanf("%d",&n)){        int countt = 5;        while(countt--){        mem(before,0);        mem(after,0);        scanf("%d%d",&a,&b);        mp.clear();        mp2.clear();        for(int i = n; i >= 1; i--){            before[i] = a % 10;            mp[a%10] = i;            a /= 10;            after[i] = b % 10;            mp2[b%10] = i;            b /= 10;        }        int ans = 0;        int tmp;        int ind;        while(check()){            for(int i = 1; i <= n; i++){                if(before[i] != after[i]){                    ans++;                    if(i == 1) ind = mp2[before[1]];                    else ind = i;                    tmp = before[1];                    mp[before[1]] = ind;                    before[1] = before[ind];                    mp[before[ind]] = 1;                    before[ind] = tmp;                    break;                }            }        }        printf("%d\n",ans);        }    }    return 0;}