UVa11925 Generating Premutations

留坑(p.254)

#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<algorithm>
#include<iostream>

using namespace std;

void setIO(const string& s) {
    freopen((s + ".in").c_str(), "r", stdin);
    freopen((s + ".out").c_str(), "w", stdout);
}
template<typename Q> Q read(Q& x) {
    static char c, f;
    for(f = 0; c = getchar(), !isdigit(c); ) if(c == '-') f = 1;
    for(x = 0; isdigit(c); c = getchar()) x = x * 10 + c - '0';
    if(f) x = -x;
    return x;
}
template<typename Q> Q read() {
    static Q x; read(x); return x;
}

const int N = 300 + 10;

#include<vector>
vector<int> a, b;

//#define dprintf(s, arg...) fprintf(stderr, s, ##arg)

void p1() {
    swap(a[0], a[1]);
    putchar('1');
//    dprintf("1:");
//    for(unsigned i = 0; i < a.size(); i++) {
//        dprintf("%d ", a[i]);
//    }
//    dprintf("
");
}

void p2() {
    int t = a[0];
    a.erase(a.begin());
    a.push_back(t);
    putchar('2');
//    dprintf("2:");
//    for(unsigned i = 0; i < a.size(); i++) {
//        dprintf("%d ", a[i]);
//    }
//    dprintf("
");
}

bool ok() {
    for(unsigned i = 0; i < a.size(); i++) {
        if(a[i] ^ b[i]) return 0;
    }
    return 1;
}

int main() {
#ifdef DEBUG
    freopen("in.txt", "r", stdin);
    freopen("out.txt", "w", stdout);
#endif
    
    int n;
    while(read(n)) {
        a.clear(), b.clear();
        for(int i = 1; i <= n; i++) {
            a.push_back(i);
            b.push_back(read<int>());
        }
        if(a[1] == b[0]) p1();
        for(int i = 0; i < n; i++) {//½«µÚi¸öÒƵ½×îºó 
            while(a[0] != b[i]) p2();
            if(ok()) break;
            if(i != n-1) while(a[1] != b[i+1]) p1(), p2();
            p2();
        }
        putchar('
');
//        dprintf("
");
    }
    
    return 0;
}