Submission #1268289

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Source Code Expand

#include <bits/stdc++.h>
#define xx first
#define yy second
#define mp make_pair
#define pb push_back
#define fill( x, y ) memset( x, y, sizeof x )
#define copy( x, y ) memcpy( x, y, sizeof x )
using namespace std;

typedef long long LL;
typedef pair < int, int > pa;

inline int read()
{
	int sc = 0, f = 1; char ch = getchar();
	while( ch < '0' || ch > '9' ) { if( ch == '-' ) f = -1; ch = getchar(); }
	while( ch >= '0' && ch <= '9' ) sc = sc * 10 + ch - '0', ch = getchar();
	return sc * f;
}

const int MAXN = 200020;

int q[MAXN], p[MAXN], n, T[MAXN], f[MAXN];

int main()
{
#ifdef wxh010910
	freopen( "data.in", "r", stdin );
#endif
	n = read();
	for( int i = 1 ; i <= n ; i++ ) q[ p[ i ] = read() ] = i;
	for( int i = n - 1 ; i ; i-- )
	{
		if( !T[ i + 1 ] )
		{
			if( q[ i ] > q[ i + 1 ] ) T[ i ] = 1, f[ i ] = i + 1;
			else T[ i ] = 0;
		}
		else
		{
			int cnt = 0;
			cnt += q[ f[ i + 1 ] ] < q[ i ];
			cnt += q[ i ] < q[ i + 1 ];
			cnt += q[ i + 1 ] < q[ f[ i + 1 ] ];
			if( cnt == 2 ) T[ i ] = T[ i + 1 ], f[ i ] = f[ i + 1 ];
			else T[ i ] = T[ i + 1 ] + 1, f[ i ] = i + 1;
		}
	}
	return printf( "%d\n", T[ 1 ] ), 0;
}

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