Codeforces Round #416 (Div. 2) ABC

打了一个半小时...做出来两道傻逼题。一道傻逼DP给WA了...2333

【A】

手工模拟，WA了一次...

//codeforces A. Vladik and Courtesy#include<cstdio>#include<cstring>#include<iostream>#include<algorithm>#define ll long long#define M(a) memset(a,0,sizeof a)#define fo(i,j,k) for(i=j;i<=k;i++)using namespace std;const int mxn=1e9;int a,b;int main(){int i,j;scanf("%d%d",&a,&b);fo(i,1,mxn){if(i&1) a-=i;else b-=i;if(a<0) return puts("Vladik"),0;if(b<0) return puts("Valera"),0;}}

【B】

n^2暴力，反正能过

//B.Vladik and Complicated Book#include<cstdio>#include<cstring>#include<iostream>#include<algorithm>#define ll long long#define M(a) memset(a,0,sizeof a)#define fo(i,j,k) for(i=j;i<=k;i++)using namespace std;const int mxn=100005;int n,m,a[mxn];int main(){int i,j,l,r,x;scanf("%d%d",&n,&m);fo(i,1,n) scanf("%d",&a[i]);while(m--){scanf("%d%d%d",&l,&r,&x);int cnt=0;fo(j,l,r){if(a[j]<a[x]) cnt++;if(cnt>x-l) break;}if(cnt==x-l) printf("Yes\n");else printf("No\n");}return 0;}

【C】

预处理出所有合法区间以及n^2个区间的异或值，线性dp一下...

预处理写挂了一次2333

//C#include<vector>#include<cstdio>#include<cstring>#include<iostream>#include<algorithm>#define ll long long#define M(a) memset(a,0,sizeof a)#define fo(i,j,k) for(i=j;i<=k;i++)using namespace std;const int mxn=5005;vector <int> v[mxn];bool ok[mxn][mxn],vis[mxn];int ans,n,a[mxn],L[mxn],R[mxn],num[mxn],cnt[mxn];int dp[mxn],xo[mxn][mxn];int main(){int i,j;scanf("%d",&n);memset(L,0x3f,sizeof L);fo(i,1,n){scanf("%d",&a[i]);num[a[i]]++;L[a[i]]=min(L[a[i]],i);R[a[i]]=max(R[a[i]],i);}fo(i,1,n){int sum=0,now=0;M(vis),M(cnt);fo(j,i,n){if(!vis[a[j]]) sum++,vis[a[j]]=1;cnt[a[j]]++;if(cnt[a[j]]==num[a[j]]) now++;if(now==sum) ok[i][j]=1,v[j].push_back(i);}}fo(i,1,n){M(vis);int x=0;fo(j,i,n){if(!vis[a[j]]) x^=a[j];xo[i][j]=x,vis[a[j]]=1;}}fo(i,1,n){dp[i]=dp[i-1];for(j=0;j<v[i].size();j++){int x=v[i][j];dp[i]=max(dp[i],dp[x-1]+xo[x][i]);}}printf("%d\n",dp[n]);return 0;}/*85 1 3 1 5 2 4 2*/