Submission #800482

#	Time	Username	Problem	Language	Result	Execution time	Memory
800482		Dan4Life	Sorting (IOI15_sorting)	C++17	100 / 100	227 ms	23052 KiB

sorting

#include <bits/stdc++.h>
using namespace std;
const int N = (int)2e5+10;
int n, a[N], p[N], vis[N];
 
bool chk(int m, int A[], int X[], int Y[], int P[], int Q[]){
    for(int i = 0; i < n; i++) a[i] = A[i];
    for(int i = 0; i < m; i++) swap(a[X[i]],a[Y[i]]), P[i]=Q[i]=0;
    for(int i = 0; i < n; i++) p[a[i]]=i, vis[i]=0;
    vector<array<int,2>> v; v.clear();
    for(int i = 0; i < n; i++){
        if(vis[i] or i==a[i]) continue; int j = i;
        while(!vis[j]){
            if(!vis[a[j]]) v.push_back({j,a[j]}); 
            vis[j] = 1; j=a[j];
        }
    }
    if(v.size()>m) return 0;
    for(int i = 0; i < n; i++) a[i]=A[i], p[a[i]]=i;
    for(int i = 0; i < m; i++){
        swap(a[X[i]],a[Y[i]]), swap(p[a[X[i]]],p[a[Y[i]]]);
        if(i<v.size()){
            P[i] = p[v[i][0]], Q[i] = p[v[i][1]]; 
            swap(a[P[i]],a[Q[i]]), swap(p[a[P[i]]],p[a[Q[i]]]);
        }
    }
    return 1;
}

int findSwapPairs(int N, int A[], int m, int X[], int Y[], int P[], int Q[]) {
    n = N; int l = 0, r = m;
    while(l<r){
        int mid = (l+r)/2;
        if(chk(mid,A,X,Y,P,Q)) r=mid;
        else l=mid+1;
    }
    chk(l,A,X,Y,P,Q); return l;
}

Compilation message (stderr)

sorting.cpp: In function 'bool chk(int, int*, int*, int*, int*, int*)':
sorting.cpp:12:9: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
   12 |         if(vis[i] or i==a[i]) continue; int j = i;
      |         ^~
sorting.cpp:12:41: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'if'
   12 |         if(vis[i] or i==a[i]) continue; int j = i;
      |                                         ^~~
sorting.cpp:18:16: warning: comparison of integer expressions of different signedness: 'std::vector<std::array<int, 2> >::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   18 |     if(v.size()>m) return 0;
      |        ~~~~~~~~^~
sorting.cpp:22:13: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::array<int, 2> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   22 |         if(i<v.size()){
      |            ~^~~~~~~~~
sorting.cpp: In function 'int findSwapPairs(int, int*, int, int*, int*, int*, int*)':
sorting.cpp:30:23: warning: declaration of 'N' shadows a global declaration [-Wshadow]
   30 | int findSwapPairs(int N, int A[], int m, int X[], int Y[], int P[], int Q[]) {
      |                   ~~~~^
sorting.cpp:3:11: note: shadowed declaration is here
    3 | const int N = (int)2e5+10;
      |           ^

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