Submission #43775

#	Time	Username	Problem	Language	Result	Execution time	Memory
43775		PowerOfNinjaGo	Sorting (IOI15_sorting)	C++14	100 / 100	611 ms	21048 KiB

sorting

//Power Of Ninja Go
#include <bits/stdc++.h>
#ifdef atom
#include "grader.cpp"
#else
#include "sorting.h"
#endif
using namespace std;
typedef long long ll; typedef pair<int, int> ii;
#define X first
#define Y second
#define vi vector<int>
#define vii vector< ii >
#define pb push_back
const int maxn = 2e5+5;
int a[3*maxn], b[3*maxn];
int x[3*maxn], y[3*maxn];
int arr[maxn];
int revnow[maxn], realnow[maxn], realend[maxn], revend[maxn];
int n, m;
bool works(int k)
{
    //printf("try %d\n", k);
    for(int i = 0; i< n; i++)
    {
        realend[i] = arr[i];
        realnow[i] = arr[i];
        revnow[arr[i]] =  i;
        revend[arr[i]] = i;
    }
    for(int i = 0; i< k; i++)
    {
        int p = x[i], q = y[i];
        int s = realend[p], t = realend[q];
        swap(realend[p], realend[q]);
        swap(revend[s], revend[t]);
    }
    int cur = 0;
    //for(int i = 0; i< n; i++) printf("%d %d\n", realnow[i], realend[i]);
    for(int i = 0; i< k; i++)
    {
        //printf("move %d\n", i);
        int p = x[i], q = y[i];
        int s = realnow[p], t = realnow[q];
        swap(revnow[s], revnow[t]);
        swap(realnow[p], realnow[q]);
        //for(int i = 0; i< n; i++) printf("%d %d\n", realnow[i], realend[i]);
        while(cur< n && realend[cur] == cur)
        {
            cur++;
            continue;
        }
        if(cur< n)
        {

            int rep = realend[cur];
            // swap rep and cur in the original array
            int s = revnow[rep], t = revnow[cur];
            swap(realnow[s], realnow[t]);
            swap(revnow[rep], revnow[cur]);
            a[i] = s, b[i] = t;
            //printf("swap %d %d\n", s, t);
            //swap rep and cur in the final array
            s = cur, t = revend[cur];
            //printf("swapend %d %d\n", s, t);
            swap(realend[s], realend[t]);
            swap(revend[rep], revend[cur]);
            cur++;
        }
        else a[i] = b[i] = 0;
        while(cur< n && realend[cur] == cur)
        {
            cur++;
            continue;
        }
    }
    return cur == n;
}
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< N; i++) arr[i] = S[i];
    for(int i = 0; i< M; i++) x[i] = X[i], y[i] = Y[i];
    bool alreadySorted = 1;
    for(int i = 0; i< N; i++) if(arr[i] != i) alreadySorted = 0;
    if(alreadySorted)
    {
        return 0;
    }
    int lo = 1, hi = M;
    while(lo< hi)
    {
        int mid = (lo+hi)/2;
        if(works(mid)) hi = mid;
        else lo = mid+1;
    }
    works(lo);
    for(int i = 0; i< lo; i++) P[i] = a[i], Q[i] = b[i];
    return lo;
}

Compilation message (stderr)

sorting.cpp: In function 'bool works(int)':
sorting.cpp:58:17: warning: declaration of 's' shadows a previous local [-Wshadow]
             int s = revnow[rep], t = revnow[cur];
                 ^
sorting.cpp:44:13: note: shadowed declaration is here
         int s = realnow[p], t = realnow[q];
             ^
sorting.cpp:58:34: warning: declaration of 't' shadows a previous local [-Wshadow]
             int s = revnow[rep], t = revnow[cur];
                                  ^
sorting.cpp:44:29: note: shadowed declaration is here
         int s = realnow[p], t = realnow[q];
                             ^

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