Submission #99206

#	Time	Username	Problem	Language	Result	Execution time	Memory
99206		eriksuenderhauf	Sorting (IOI15_sorting)	C++11	100 / 100	748 ms	30724 KiB

sorting

//#pragma GCC optimize("O3")
#include <bits/stdc++.h>
#include "sorting.h"
#define pii pair<int, int>
#define pll pair<long long, long long>
#define vii vector<pii>
#define vi vector<int>
#define pb push_back
#define mp make_pair
#define fi first
#define se second
using namespace std;
typedef long long ll;
const int MAXN = 1e6 + 5;
int n = 0, m = 0;
int x[MAXN], y[MAXN], p[MAXN], q[MAXN], sz[MAXN], ind2[MAXN];
int p2[MAXN], q2[MAXN], par[MAXN], a[MAXN], ind[MAXN];

int qry(int x) {
    if (x == par[x]) return x;
    return par[x] = qry(par[x]);
}

void join(int x, int y) {
    x = qry(x), y = qry(y);
    if (x == y) return;
    if (sz[x] > sz[y]) swap(x, y);
    sz[y] += sz[x];
    par[x] = y;
}

bool solve(int cnt) {
    for (int i = 0; i < n; i++)
        par[i] = i, sz[i] = 1, ind[i] = i;
    for (int i = 0; i < cnt; i++) {
        swap(a[x[i]], a[y[i]]);
        swap(ind[x[i]], ind[y[i]]);
    }
    for (int i = 0; i < n; i++)
        join(i, a[i]);
    vii ans;
    int cnt2 = 0;
    for (int i = 0; i < n; i++) {
        if (qry(i) != i)
            continue;
        cnt2 += sz[i] - 1;
        int nx = a[i], pr = i;
        while (nx != i) {
            ans.pb({ind[i], ind[nx]});
            pr = nx;
            nx = a[nx];
        }
    }
    while (ans.size() < cnt)
        ans.pb({0, 0});
    for (int i = 0; i < n; i++)
        ind[i] = i, ind2[i] = i;
    for (int i = 0; i < cnt; i++) {
        swap(ind2[ind[x[i]]], ind2[ind[y[i]]]);
        swap(ind[x[i]], ind[y[i]]);
        p[i] = ind2[ans[i].fi], q[i] = ind2[ans[i].se];
    }
    return (ans.size() == cnt);
}

void cp(int cnt) {
    for (int i = 0; i < cnt; i++)
        p2[i] = p[i], q2[i] = q[i];
}

int findSwapPairs(int N, int S[], int M, int X[], int Y[], int P[], int Q[]) {
    n = N, m = M;
    int lo = 0, hi = n - 1, ans = -1;
    for (int i = 0; i < m; i++)
        x[i] = X[i], y[i] = Y[i];
    while (lo <= hi) {
        int mi = (lo + hi) / 2;
        for (int i = 0; i < n; i++)
            a[i] = S[i];
        if (solve(mi)) {
            hi = mi - 1, ans = mi;
            cp(ans);
        } else
            lo = mi + 1;
    }
    for (int i = 0; i < ans; i++)
        P[i] = p2[i], Q[i] = q2[i];
    return ans;
}

Compilation message (stderr)

sorting.cpp: In function 'int qry(int)':
sorting.cpp:19:14: warning: declaration of 'x' shadows a global declaration [-Wshadow]
 int qry(int x) {
              ^
sorting.cpp:16:5: note: shadowed declaration is here
 int x[MAXN], y[MAXN], p[MAXN], q[MAXN], sz[MAXN], ind2[MAXN];
     ^
sorting.cpp: In function 'void join(int, int)':
sorting.cpp:24:23: warning: declaration of 'y' shadows a global declaration [-Wshadow]
 void join(int x, int y) {
                       ^
sorting.cpp:16:14: note: shadowed declaration is here
 int x[MAXN], y[MAXN], p[MAXN], q[MAXN], sz[MAXN], ind2[MAXN];
              ^
sorting.cpp:24:23: warning: declaration of 'x' shadows a global declaration [-Wshadow]
 void join(int x, int y) {
                       ^
sorting.cpp:16:5: note: shadowed declaration is here
 int x[MAXN], y[MAXN], p[MAXN], q[MAXN], sz[MAXN], ind2[MAXN];
     ^
sorting.cpp: In function 'bool solve(int)':
sorting.cpp:47:24: warning: variable 'pr' set but not used [-Wunused-but-set-variable]
         int nx = a[i], pr = i;
                        ^~
sorting.cpp:54:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     while (ans.size() < cnt)
            ~~~~~~~~~~~^~~~~
sorting.cpp:63:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     return (ans.size() == cnt);
             ~~~~~~~~~~~^~~~~~

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