牛客小白月赛21I I love you
思路:
dp。dp[i]=(dp[i]+(s==‘x’)*dp[i-1])%mod。x为当前位置上要求的字母。
代码:
#include<bits/stdc++.h>
#define pii pair<int,int>
#define ll long long
const int N=1e6+10;
const int mod=20010905;
const int maxn=0x3f3f3f3f;
const int minn=0xc0c0c0c0;
const int inf=99999999;
using namespace std;
string s;
ll f[10]={0};
int main()
{
ios::sync_with_stdio(false);
cin.tie(0);cout.tie(0);
int i;
cin>>s;
for(i=0;i<=s.length();i++)
{
if(s[i]>='A' && s[i]<='Z')
s[i]=s[i]-'A'+'a';
f[1]=f[1]+(s[i]=='i');
f[2]=(f[2]+(s[i]=='l')*f[1])%mod;
f[3]=(f[3]+(s[i]=='o')*f[2])%mod;
f[4]=(f[4]+(s[i]=='v')*f[3])%mod;
f[5]=(f[5]+(s[i]=='e')*f[4])%mod;
f[6]=(f[6]+(s[i]=='y')*f[5])%mod;
f[7]=(f[7]+(s[i]=='o')*f[6])%mod;
f[8]=(f[8]+(s[i]=='u')*f[7])%mod;
}
cout<<f[8]%mod<<endl;
return 0;
}