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2021女生赛B

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// Problem: B. 攻防演练
// Contest: Codeforces - 2021年中国大学生程序设计竞赛女生专场
// URL: https://codeforces.com/gym/103389/problem/B
// Memory Limit: 512 MB
// Time Limit: 1000 ms
// 
// Powered by CP Editor (https://cpeditor.org)

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;typedef unsigned long long ull;
typedef pair<ll,ll>PLL;typedef pair<int,int>PII;typedef pair<double,double>PDD;
#define I_int ll
inline ll read(){ll x=0,f=1;char ch=getchar();while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}return x*f;}
#define read read()
#define rep(i, a, b) for(int i=(a);i<=(b);++i)
#define dep(i, a, b) for(int i=(a);i>=(b);--i)
ll ksm(ll a,ll b,ll p){ll res=1;while(b){if(b&1)res=res*a%p;a=a*a%p;b>>=1;}return res;}
const int maxn=2e5+7,maxm=1e6+7,mod=1e9+7;

char s[maxn];
int ne[maxn][27],mp[27],dp[maxn][23];

int main(){
	int m=read,n=read;
	scanf("%s",s+1);
	for(int i=0;i<=26;i++) mp[i]=n+1,ne[n][i]=n+1;
	for(int i=n;i;i--){
		int now=s[i]-'a';
		ne[i][now]=mp[now];
		mp[now]=i;
		for(int j=0;j<m;j++){
			ne[i-1][j]=mp[j];
		}
	}
	for(int i=0;i<=n;i++){
		int now=0;
		for(int j=0;j<m;j++) now=max(now,ne[i][j]);
		dp[i][0]=now;
	}
	for(int i=0;i<22;i++) dp[n][i]=dp[n+1][i]=n+1;
	for(int j=1;j<22;j++)
		for(int i=0;i<=n;i++){
			dp[i][j]=dp[dp[i][j-1]][j-1];
		}
	int q=read;
	while(q--){
		int l=read-1,r=read;
		int ans=1;
		for(int i=21;i>=0;i--){
		//	cout<<i<<" "<<l<<" "<<dp[l][i]<<" "<<ans<<endl;
			if(dp[l][i]<=r){
				
				l=dp[l][i];
				ans=ans+(1<<i);
			}
		}
			
		cout<<ans<<endl;
	}
	
	
	return 0;
}

2020沈阳ICPC D

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#include<bits/stdc++.h>
using namespace std;
typedef long long ll;typedef unsigned long long ull;
typedef pair<ll,ll>PLL;typedef pair<int,int>PII;typedef pair<double,double>PDD;
#define I_int ll
inline ll read(){ll x=0,f=1;char ch=getchar();while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}return x*f;}
#define read read()
#define rep(i, a, b) for(int i=(a);i<=(b);++i)
#define dep(i, a, b) for(int i=(a);i>=(b);--i)
ll ksm(ll a,ll b,ll p){ll res=1;while(b){if(b&1)res=res*a%p;a=a*a%p;b>>=1;}return res;}
const int maxn=1e6+7;

char s[maxn];
ll n,ans,sum;

void dfs(int u,int cnt0,int cnt1,int now){
	if(ans>=100||cnt0>sum||cnt1>sum) return ;
	if(u==n){
		cout<<s<<endl;
		ans++;
		return ;
	}
	if(now%2==0){
		s[u]='b';
		dfs(u+1,cnt0+1,cnt1,now);
		s[u]='r';
		dfs(u+1,cnt0,cnt1+1,now^1);
	}
	else{
		s[u]='b';
		dfs(u+1,cnt0,cnt1+1,now);
		s[u]='r';
		dfs(u+1,cnt0+1,cnt1,now^1);
	}
}

int main(){
	n=read;
	sum=(n+1)/2;
	ll tmp1=(n+1)/2,tmp2=(n+1)/2;
	if((n+1)%2) sum++,tmp1++;
	cout<<tmp1*tmp2<<endl;
	dfs(0,1,0,0);
    return 0;
}
/*

*/