【每日一题】 UVA - 1587 Box 二维有点偏序的感觉

一开始用set存xjb分类讨论，然后wa，

然后简化了一点，改用vector，然wa

最后又发现没有初始化，然wa

wa了一个半小时

最后看了题解orz

然后找了一组样例把自己的代码改对了

/*

1 1
1 1
1 1
1 1
1 2
1 2

*/

正统题解：不妨设三条边为a<=b<=c， 那么对每个面（边对）sort后，必然得到 ab ab ac ac bc bc 然后照着这个序列写六个判断就好了orz

#define _CRT_SECURE_NO_WARNINGS
#include<cmath>
#include<iostream>
#include<stdio.h>
#include<algorithm>
#include<cstring>
#include<stack>
#include<vector>
#include<string.h>
#include<queue>
#include<string>
#include<set>
#include<map>
using namespace std;
typedef long long ll;
#define mod 1000000007
#define rep(i,t,n)  for(int i =(t);i<=(n);++i)
#define per(i,n,t)  for(int i =(n);i>=(t);--i)
#define mmm(a,b) memset(a,b,sizeof(a))
#define eps 1e-6
#define pb push_back

#define mp make_pair
#define x first
#define y second
pair<int, int> a[];
int main() {
    while (cin >> a[].x >> a[].y){

        rep(i, , )scanf("%d%d", &a[i].x, &a[i].y);
        rep(i, , )if(a[i].x>a[i].y)swap(a[i].x,a[i].y);
        sort(a + , a + );
        puts(a[] == a[] && a[] == a[] && a[] == a[] && a[].x==a[].x&&a[].y==a[].y&&a[].x==a[].y?"POSSIBLE":"IMPOSSIBLE");

}
}
/*
POSSIBLE
IMPOSSIBLE
*/

第一版代码，先判每个面出现了两遍，再把不同的三个面找出来，按有几个面是正方形分类

#define _CRT_SECURE_NO_WARNINGS
#include    <cmath>
#include <iostream>
#include    <stdio.h>
#include<algorithm>
#include        <map>
#include     <cstring>
#include      <time.h>
#include    <string>
#include    <vector>
#include <set>
using namespace std;
#define rep(i,t,n)  for(int i =(t);i<=(n);++i)
#define per(i,n,t)  for(int i =(n);i>=(t);--i)
#define mmm(a,b) memset(a,b,sizeof(a))
const double pi = acos(-1.0);
const int maxn =  + ;
int n,m;

int main()
{

    int x, y;

    while (cin >> x >> y){
        set<int> S[];
        vector < set<int>> V;
        S[].insert(x), S[].insert(y);
        rep(i, , ) {

            cin >> x >> y;
            S[i].insert(x), S[i].insert(y);
    }
        int f[];
        mmm(f, );
        int vis[]; mmm(vis, );
        rep(i, , )rep(j, , )if (i != j) {
            if (S[i] == S[j]) { f[i] = ; if (!vis[i]&&!vis[j]) { V.push_back(S[i]); vis[j] = ; vis[i] = ;} }
        }
        rep(i, , )if (!f[i]) { f[] = ; }
        if (f[] == ) { puts("IMPOSSIBLE"); continue; }
        int cnt=;
        rep(i, , )if (V[i].size() == )cnt++;
        if (cnt == ) { if (V[] == V[] && V[] == V[]) puts("POSSIBLE"); else puts("IMPOSSIBLE"); continue; }
        if (cnt == ) {
            vector < set<int>> T;
            for (auto t : V)if (t.size() == ) { T.push_back(t); }
            if(*T.begin()==*T.rbegin()) { puts("POSSIBLE"); continue; }else { puts("IMPOSSIBLE"); continue; }
        }
        if(cnt==) { puts("IMPOSSIBLE"); continue; }
        if (cnt == ) {
            int ok = ;
            vector < int> T;
            rep(i, , )if (*V[].begin() == *V[i].begin())T.push_back(*V[i].rbegin());
            else if (*V[].begin() == *V[i].rbegin())T.push_back(*V[i].begin());
            rep(i, , )if (*V[].rbegin() == *V[i].begin())T.push_back(*V[i].rbegin());
            else if (*V[].rbegin() == *V[i].rbegin())T.push_back(*V[i].begin());
            //else ok = 0;
            if(T.size()!=){ puts("IMPOSSIBLE"); continue; }
            if(T.front()!=T.back()) { puts("IMPOSSIBLE"); continue; }
            else { puts("POSSIBLE"); continue; }
        }
    }
    cin >> n;
    return ;
}
/*

1 1
2 1
2 1
1 1
1 1
1 1
*/

第二版代码：用vector存，并且简化了分类：要么可以 要么不可能//废话

#include<stdio.h>
#include<string.h>
#include<math.h>
#include<algorithm>
#include<iostream>
#include<queue>
#include<set>
#include<vector>
using namespace std;
typedef long long ll;
#define rep(i,t,n)  for(int i =(t);i<=(n);++i)
#define per(i,n,t)  for(int i =(n);i>=(t);--i)
#define mmm(a,b) memset(a,b,sizeof(a))
int main()
{

    int x, y;
    while (cin >> x >> y) {
        vector < vector<int>> V;
        vector<int> v[];
        if (x > y)swap(x, y);
        v[].push_back(x); v[].push_back(y);
        rep(i, , ) {

            cin >> x >> y;
            if (x > y)swap(x, y);
            v[i].push_back(x); v[i].push_back(y);
        }
        int f[]; int vis[]; mmm(vis, );
        mmm(f, );
        rep(i, , )rep(j, , )if (i != j) {
            if (v[i] == v[j]) { f[i] = ; if (!vis[i]&&!vis[j]) { V.push_back(v[i]); vis[j] = ; vis[i] = ;}  }
        }
        rep(i, , )if (!f[i]) { f[] = ; }
        if (f[] == ) { puts("IMPOSSIBLE"); continue; }
        int ok = ;
        int t = ;
        int x = ;
        if (V[].front() == V[].front())t = V[].back(); else if (V[].front() == V[].back())t = V[].front(); else {
            x = ;
            if (V[].front() == V[].front())t = V[].back(); else if (V[].front() == V[].back())t = V[].front(); else ok = ;
        }
        int t2 = ;
        if (t == V[x].front())t2 = V[x].back(); else if (t == V[x].back())t2 = V[x].front(); else {
            ok = ;
        }
        if (t2 != V[].back())ok = ;
        if (ok)puts("POSSIBLE");
        else puts("IMPOSSIBLE");
    }
    return ;
}