Submission #252296

#	Time	Username	Problem	Language	Result	Execution time	Memory
252296		Hehehe	Sorting (IOI15_sorting)	C++14	100 / 100	414 ms	30496 KiB

sorting

#include<bits/stdc++.h> //:3
using namespace std;
typedef long long ll;
#define all(a) (a).begin(), (a).end()
#define ff first
#define ss second
#define pb push_back
#define mp make_pair
#define rc(s) return cout<<s,0
#define pi pair <int, int>
#define sz(x) (int)((x).size())
#include "sorting.h"

const int dx[] = {0, 1, 0, -1};
const int dy[] = {1, 0, -1, 0};

const ll H = 1e6 + 11;

//ifstream in(".in");
//ofstream out(".out");

int pos[H], n, m;
pi query[H], ans[H], a[H];
/*
bool check(int t, int S[]){

    int in[n + 11], out[n + 11];

    for(int i = 0; i < n; i++){
        in[i] = out[i] = S[i];
    }

    for(int i = 0; i < t; i++){
        swap(out[query[i].ff], out[query[i].ss]);
    }

    bool viz[n + 11];
    memset(viz, 0, sizeof(viz));

    int k = 0;
    for(int i = 0; i < n; i++){

        if(viz[i])continue;

        vector<int>cur;

        int v = out[i];
        while(v != i){
            cur.push_back(v);
            v = out[v];
        }
        cur.push_back(v);

        for(int j = sz(cur) - 1; j > 0; j--){
            a[k++] = {cur[0], cur[j]};
        }

        for(auto it : cur)viz[it] = 1;
    }

    if(k > t)return 0;

    for (int i = 0; i < n; ++i){
        pos[in[i]] = i;
    }

    for(int i = 0; i < k; i++){

        //His move
        int x = query[i].ff, y = query[i].ss;
        swap(in[x], in[y]);
        pos[in[x]] = x;
        pos[in[y]] = y;

        //My move
        x = pos[a[i].ff], y = pos[a[i].ss];
        swap(in[x], in[y]);
        pos[in[x]] = x;
        pos[in[y]] = y;

        ans[i] = {x, y};
    }

    while(k < t)ans[k++] = {0, 0};

    return 1;

} */
bool check(int t, int S[]){

    int out[n], in[n];

    for (int i = 0; i < n; ++i)
        out[i] = in[i] = S[i];

    for (int id = 0; id < t; ++id) {
        int i = query[id].ff, j = query[id].ss;
        swap(out[i], out[j]);
    }

    bool us[n];
    memset(us, false, sizeof us);

    int cnt = 0;

    for (int i = 0; i < n; ++i) {
        if (us[i])
            continue;

        vector<int> ord;
        int v = out[i];
        while (v != i) {
            ord.pb(v);
            us[v] = true;
            v = out[v];
        }
        ord.pb(v);
        us[v] = true;

        for (int j = sz(ord) - 1; j > 0; --j)
            a[cnt++] = mp(ord[0], ord[j]);
    }

    if (cnt > t)return 0;

    for (int i = 0; i < n; ++i)
        pos[in[i]] = i;

    for (int id = 0; id < cnt; ++id) {

        int i = query[id].ff, j = query[id].ss;
        swap(in[i], in[j]);
        pos[in[i]] = i;
        pos[in[j]] = j;


        i = pos[a[id].ff]; j = pos[a[id].ss];
        ans[id] = mp(i, j);
        swap(in[i], in[j]);
        pos[in[i]] = i;
        pos[in[j]] = j;
    }

    while (cnt < t)
        ans[cnt++] = mp(0, 0);

    return true;
}

int findSwapPairs(int N, int S[], int M, int X[], int Y[], int P[], int Q[]) {

    n = N; m = M;

    for(int i = 0; i < m; i++){
        query[i].ff = X[i];
        query[i].ss = Y[i];
    }
    
    int l = -1, r = M;
    while (r - l > 1) {
        int m = (l + r) >> 1;
        if (check(m, S)) {
            r = m;
        } else {
            l = m;
        }
    }
    check(r, S);


    for(int i = 0; i < r; i++){
        P[i] = ans[i].ff;
        Q[i] = ans[i].ss;
    }

    return r;
}

Compilation message (stderr)

sorting.cpp: In function 'int findSwapPairs(int, int*, int, int*, int*, int*, int*)':
sorting.cpp:161:13: warning: declaration of 'm' shadows a global declaration [-Wshadow]
         int m = (l + r) >> 1;
             ^
sorting.cpp:22:16: note: shadowed declaration is here
 int pos[H], n, m;
                ^

• Subtask 1: 8 / 8
• Subtask 2: 12 / 12
• Subtask 3: 16 / 16
• Subtask 4: 18 / 18
• Subtask 5: 20 / 20
• Subtask 6: 26 / 26