Codeforces 605A.Sorting Railway Cars【技巧】

本文介绍了一个火车车厢排序问题,目标是最少操作次数将车厢按编号升序排列。可以通过消失并传送车厢到首尾来实现排序,挑战在于找到最优方案。

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A. Sorting Railway Cars
time limit per test
2 seconds
memory limit per test
256 megabytes
input
standard input
output
standard output

An infinitely long railway has a train consisting of n cars, numbered from 1 to n (the numbers of all the cars are distinct) and positioned in arbitrary order. David Blaine wants to sort the railway cars in the order of increasing numbers. In one move he can make one of the cars disappear from its place and teleport it either to the beginning of the train, or to the end of the train, at his desire. What is the minimum number of actions David Blaine needs to perform in order to sort the train?

Input

The first line of the input contains integer n (1 ≤ n ≤ 100 000) — the number of cars in the train.

The second line contains n integers pi (1 ≤ pi ≤ npi ≠ pj if i ≠ j) — the sequence of the numbers of the cars in the train.

Output

Print a single integer — the minimum number of actions needed to sort the railway cars.

Examples
input
5
4 1 2 5 3
output
2
input
4
4 1 3 2
output
2
Note

In the first sample you need first to teleport the 4-th car, and then the 5-th car to the end of the train.

AC-code:
//#include<bits/stdc++.h>  
#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
using namespace std;
int main(){
	int n,i,j,flag,a,dp[100005];
	cin>>n;
	flag=1;
	memset(dp,0,sizeof(dp));
	for(i=0;i<n;i++){
		cin>>a;
		dp[a]=dp[a-1]+1;
	}
	sort(dp+1,dp+n+1);
	cout<<n-dp[n]<<endl;
	return 0;
} 


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