P2101 命运石之门的选择 题解

草了

我不得不承认我孤陋寡闻了

因为这是我见到的第一道卡MLE的题

前几次提交 \((60 - 80pts):\)

#include<algorithm>
#include<bitset>
#include<cctype>
#include<cerrno>
#include<clocale>
#include<cmath>
#include<complex>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<ctime>
#include<deque>
#include<exception>
#include<fstream>
#include<functional>
#include<limits>
#include<list>
#include<map>
#include<iomanip>
#include<ios>
#include<iosfwd>
#include<iostream>
#include<istream>
#include<ostream>
#include<queue>
#include<set>
#include<sstream>
#include<stack>
#include<stdexcept>
#include<streambuf>
#include<string>
#include<utility>
#include<vector>
#include<cwchar>
#include<cwctype>
#include<chrono>
#include<random>
#include<unordered_map>
using namespace std;

const int N=5001;
int n;
int h[N],f[N][N][2];

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

int dfs(int l,int r,int low){
	if(l>r)
        return 0;
	if(l==r){
		if(low==h[l])
            return 0;
		else
            return 1;
	}
	return min(r-l+1,f[l][r][0]-low+dfs(l,f[l][r][1]-1,f[l][r][0])+dfs(f[l][r][1]+1,r,f[l][r][0]));
}

int main(){
	n=read();
	for(int i=1;i<=n;i++){
        h[i]=read();
        f[i][i][0]=h[i];
        f[i][i][1]=i;
    }
	for(int i=1;i<n;i++){
	    for(int j=i+1;j<=n;j++){
		    if(f[i][j-1][0]<h[j]){
                f[i][j][1]=f[i][j-1][1];
                f[i][j][0]=f[i][j-1][0];
            }
		    else{
                f[i][j][1]=j;
                f[i][j][0]=h[j];
            }
        }
    }
	printf("%d",dfs(1,n,0));
	return 0;
}

看看测评记录

每次提交还nmd不一样

看了题解才会 \(qwq\)

\((100pts):\)

#include<algorithm>
#include<bitset>
#include<cctype>
#include<cerrno>
#include<clocale>
#include<cmath>
#include<complex>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<ctime>
#include<deque>
#include<exception>
#include<fstream>
#include<functional>
#include<limits>
#include<list>
#include<map>
#include<iomanip>
#include<ios>
#include<iosfwd>
#include<iostream>
#include<istream>
#include<ostream>
#include<queue>
#include<set>
#include<sstream>
#include<stack>
#include<stdexcept>
#include<streambuf>
#include<string>
#include<utility>
#include<vector>
#include<cwchar>
#include<cwctype>
#include<chrono>
#include<random>
#include<unordered_map>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;

const int N=5010;
int n;
ll h[N];

inline ll read(){
        ll x=0,y=1;
        char c=getchar();
    while (c<'0'||c>'9'){
        if(c=='-')
            y=-1;
        c=getchar();
    }
    while(c>='0'&&c<='9'){
        x=x*10+c-'0';
        c=getchar();
    }
        return x*y;
}

ll dfs(int l,int r,ll high){
    if(l==r)
		return 1;
    ll ans,m=-1,tmp=r-l+1;
    for(int i=l;i<=r;i++)
    	if(m==-1||m>h[i])
			m=h[i];
    ans=m-high;
    for(int i=l;i<=r;i++){
        int mid;
        if(h[i]==m)
			continue;
		else
			for(int j=i;j<=r;j++){
            	mid=j; 
            	if(j==r||h[j+1]==m)
					break;
        	}
        ans+=dfs(i,mid,m);
        i=mid+1;
    }
    return min(tmp,ans);
}

int main(){
	n=read();
	for(int i=1;i<=n;i++)
		h[i]=read();
	printf("%lld",dfs(1,n,0));
	return 0;
}