Codeforces Round #424 (Div. 2, rated, based on VK Cup Finals)

A 检测一个序列是否为单峰

http://codeforces.com/contest/831/problem/A

按递增相等递减的顺序遍历再检查是否遍历到末尾

#include <iostream>
#include <algorithm>
#include <sstream>
#include <string>
#include <queue>
#include <cstdio>
#include <map>
#include <set>
#include <utility>
#include <stack>
#include <cstring>
#include <cmath>
#include <vector>
using namespace std;
#define pb push_back
#define scand(n) scanf("%d",&n)
#define scandd(n,m) scanf("%d%d",&n,&m)
#define scanddd(n,m,k) scanf("%d%d%d",&n,&m,&k)
#define scanlld(n) scanf("%lld",&n)
#define scanlldd(n,m) scanf("%lld%lld",&n,&m)
#define scanllddd(n,m,k) scanf("%lld%lld%lld",&n,&m,&k)
#define scanlf(n) scanf("%lf",&n)
#define scanlff(n,m) scanf("%lf%lf",&n,&m)
#define scanlfff(n,m,k) scanf("%lf%lf%lf",&n,&m,&k)
#define scans(str) scanf("%s",str)
#define ans() printf("%d",ans)
#define ansn() printf("%d\n",ans)
#define anss() printf("%d ",ans)
#define llans() printf("%lld",ans)
#define llanss() printf("%lld ",ans)
#define llansn() printf("%lld\n",ans)
#define REP(i,n) for(int i=0;i<(n);++i)
#define REA(i,qwe,ewr) for(int i=qwe;i<=ewr;++i)
#define RER(i,qwe,ewr) for(int i=qwe;i>=ewr;--i)
#define R1(i,e) for(int i=1;i<=e;++i)
#define RN(i,e) for(int i=e;i>=1;--i)
#define mst(abc,bca) memset(abc,bca,sizeof abc)
#define all(a) a.begin(),a.end()
#define pii pair<int,int>
#define mp make_pair
typedef long long ll;
inline int read()
{
int 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;
}
inline int mul_mod(int a, int b, int mo)
{
int ret;
__asm__ __volatile__ ("\tmull %%ebx\n\tdivl %%ecx\n" : "=d"(ret):"a"(a),"b"(b),"c"(mo));
return ret;
}
const int mod = 1000000007;
const double eps=1e-9;
const int INF=0x3f3f3f3f;
const int MAXN=2000+10;

int num[MAXN];
int main()
{
#ifdef LOCAL
freopen("input.txt","r",stdin);
//    freopen("output.txt","w",stdout);
#endif // LOCAL

int n;
scand(n);
R1(i,n)scand(num[i]);
int cnt=0;
bool u=1;
int i;
for(i=2;i<=n;++i)
{
if(num[i]<=num[i-1])break;
}
while(num[i]==num[i-1])i++;
while(i<=n&&num[i]<num[i-1])i++;
if(i==n+1)puts("YES");
else puts("NO");
return 0;
}

B 对每个字母有一个映射求一个字符串映射后的结果

http://codeforces.com/contest/831/problem/B

用map同时建立大小写字母的映射

#include <iostream>
#include <algorithm>
#include <sstream>
#include <string>
#include <queue>
#include <cstdio>
#include <map>
#include <set>
#include <utility>
#include <stack>
#include <cstring>
#include <cmath>
#include <vector>
using namespace std;
#define pb push_back
#define scand(n) scanf("%d",&n)
#define scandd(n,m) scanf("%d%d",&n,&m)
#define scanddd(n,m,k) scanf("%d%d%d",&n,&m,&k)
#define scanlld(n) scanf("%lld",&n)
#define scanlldd(n,m) scanf("%lld%lld",&n,&m)
#define scanllddd(n,m,k) scanf("%lld%lld%lld",&n,&m,&k)
#define scanlf(n) scanf("%lf",&n)
#define scanlff(n,m) scanf("%lf%lf",&n,&m)
#define scanlfff(n,m,k) scanf("%lf%lf%lf",&n,&m,&k)
#define scans(str) scanf("%s",str)
#define ans() printf("%d",ans)
#define ansn() printf("%d\n",ans)
#define anss() printf("%d ",ans)
#define llans() printf("%lld",ans)
#define llanss() printf("%lld ",ans)
#define llansn() printf("%lld\n",ans)
#define REP(i,n) for(int i=0;i<(n);++i)
#define REA(i,qwe,ewr) for(int i=qwe;i<=ewr;++i)
#define RER(i,qwe,ewr) for(int i=qwe;i>=ewr;--i)
#define R1(i,e) for(int i=1;i<=e;++i)
#define RN(i,e) for(int i=e;i>=1;--i)
#define mst(abc,bca) memset(abc,bca,sizeof abc)
#define all(a) a.begin(),a.end()
#define pii pair<int,int>
#define mp make_pair
typedef long long ll;
inline int read()
{
int 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;
}
inline int mul_mod(int a, int b, int mo)
{
int ret;
__asm__ __volatile__ ("\tmull %%ebx\n\tdivl %%ecx\n" : "=d"(ret):"a"(a),"b"(b),"c"(mo));
return ret;
}
const int mod = 1000000007;
const double eps=1e-9;
const int INF=0x3f3f3f3f;
const int MAXN=2000+10;

int n,k;
char s[MAXN],s2[MAXN],s3[MAXN];
map<char,char>ma;
int main()
{
#ifdef LOCAL
freopen("input.txt","r",stdin);
//    freopen("output.txt","w",stdout);
#endif // LOCAL

//    scandd(n,k);
scans(s+1);
scans(s2+1);
int n=strlen(s+1);
R1(i,n)
{
if(!ma.count(s[i]))
{
ma[ s[i] ] = s2[i];
ma[ s[i]-32 ] = s2[i]-32;
}
}
scans(s3+1);
int m =strlen(s3+1);
R1(i,m)
{
if(s3[i]>='0'&&s3[i]<='9')
{
putchar(s3[i]);continue;
}
char ch = ma[ s3[i] ];
putchar(ch);
}
return 0;
}

C

有k个变化 和 n个变化后的结果

求可能的初始值有多少种

http://codeforces.com/contest/831/problem/C

对每个bi都至少有一个合法位置 并且利用前缀和bi的位置和值可以计算出初始值

枚举一个bi是对应的ai变化的结果 再检测是否合法

#include <iostream>
#include <algorithm>
#include <sstream>
#include <string>
#include <queue>
#include <cstdio>
#include <map>
#include <set>
#include <utility>
#include <stack>
#include <cstring>
#include <cmath>
#include <vector>
using namespace std;
#define pb push_back
#define scand(n) scanf("%d",&n)
#define scandd(n,m) scanf("%d%d",&n,&m)
#define scanddd(n,m,k) scanf("%d%d%d",&n,&m,&k)
#define scanlld(n) scanf("%lld",&n)
#define scanlldd(n,m) scanf("%lld%lld",&n,&m)
#define scanllddd(n,m,k) scanf("%lld%lld%lld",&n,&m,&k)
#define scanlf(n) scanf("%lf",&n)
#define scanlff(n,m) scanf("%lf%lf",&n,&m)
#define scanlfff(n,m,k) scanf("%lf%lf%lf",&n,&m,&k)
#define scans(str) scanf("%s",str)
#define ans() printf("%d",ans)
#define ansn() printf("%d\n",ans)
#define anss() printf("%d ",ans)
#define llans() printf("%lld",ans)
#define llanss() printf("%lld ",ans)
#define llansn() printf("%lld\n",ans)
#define REP(i,n) for(int i=0;i<(n);++i)
#define REA(i,qwe,ewr) for(int i=qwe;i<=ewr;++i)
#define RER(i,qwe,ewr) for(int i=qwe;i>=ewr;--i)
#define R1(i,e) for(int i=1;i<=e;++i)
#define RN(i,e) for(int i=e;i>=1;--i)
#define mst(abc,bca) memset(abc,bca,sizeof abc)
#define all(a) a.begin(),a.end()
#define pii pair<int,int>
#define mp make_pair
typedef long long ll;
inline int read()
{
int 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;
}
inline int mul_mod(int a, int b, int mo)
{
int ret;
__asm__ __volatile__ ("\tmull %%ebx\n\tdivl %%ecx\n" : "=d"(ret):"a"(a),"b"(b),"c"(mo));
return ret;
}
const int mod = 1000000007;
const double eps=1e-9;
const int INF=0x3f3f3f3f;
const int MAXN=2000+10;

int a[MAXN];
int b[MAXN];
int pri[MAXN];
map<int,int>ma,ma2;
map<int,int>ma3;
int main()
{
#ifdef LOCAL
freopen("input.txt","r",stdin);
//    freopen("output.txt","w",stdout);
#endif // LOCAL
ll ans =0;
int n,k;
scandd(k,n);
R1(i,k)
{
scand(a[i]);
pri[i]= pri[i-1]+a[i];
}
R1(i,n)
{
scand(b[i]);
ma2[b[i] ]=1;
}
R1(i,k)
{
int cnt = n-1;
ma3.clear();
for(int j=1;cnt&&j<=k;++j)
{
if(j==i)continue;
int check = b[1] + (pri[j]-pri[i]);
if(!ma2.count(check)||check==b[1])continue;
if(!ma3.count(check))
--cnt,ma3[check]=1;
}
if(!cnt&&!ma.count(b[1]-pri[i]))
++ans,ma[b[1]-pri[i]]=1;
}
llans();
return 0;
}

D

有n个人 k个钥匙的位置 办公室的位置p

求所有人都能拿到1个钥匙并到达办公室的最小时间

http://codeforces.com/contest/831/problem/D

对人和钥匙的位置排序

二分答案并检测是否合法

从左往右开始贪心

每个人选择尽量左边的钥匙 保证右边的人尽量能选到x范围内的1把

#include <iostream>
#include <algorithm>
#include <sstream>
#include <string>
#include <queue>
#include <cstdio>
#include <map>
#include <set>
#include <utility>
#include <stack>
#include <cstring>
#include <cmath>
#include <vector>
using namespace std;
#define pb push_back
#define scand(n) scanf("%d",&n)
#define scandd(n,m) scanf("%d%d",&n,&m)
#define scanddd(n,m,k) scanf("%d%d%d",&n,&m,&k)
#define scanlld(n) scanf("%lld",&n)
#define scanlldd(n,m) scanf("%lld%lld",&n,&m)
#define scanllddd(n,m,k) scanf("%lld%lld%lld",&n,&m,&k)
#define scanlf(n) scanf("%lf",&n)
#define scanlff(n,m) scanf("%lf%lf",&n,&m)
#define scanlfff(n,m,k) scanf("%lf%lf%lf",&n,&m,&k)
#define scans(str) scanf("%s",str)
#define ans() printf("%d",ans)
#define ansn() printf("%d\n",ans)
#define anss() printf("%d ",ans)
#define llans() printf("%lld",ans)
#define llanss() printf("%lld ",ans)
#define llansn() printf("%lld\n",ans)
#define REP(i,n) for(int i=0;i<(n);++i)
#define REA(i,qwe,ewr) for(int i=qwe;i<=ewr;++i)
#define RER(i,qwe,ewr) for(int i=qwe;i>=ewr;--i)
#define R1(i,e) for(int i=1;i<=e;++i)
#define RN(i,e) for(int i=e;i>=1;--i)
#define mst(abc,bca) memset(abc,bca,sizeof abc)
#define all(a) a.begin(),a.end()
#define pii pair<int,int>
#define mp make_pair
typedef long long ll;
inline int read()
{
int 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;
}
inline int mul_mod(int a, int b, int mo)
{
int ret;
__asm__ __volatile__ ("\tmull %%ebx\n\tdivl %%ecx\n" : "=d"(ret):"a"(a),"b"(b),"c"(mo));
return ret;
}
const int mod = 1000000007;
const double eps=1e-9;
const int INF=0x3f3f3f3f;
const int MAXN=2000+10;

ll a[MAXN],b[MAXN];
int num[MAXN];ll n,k,p;
ll sum (int i,int j)
{
return abs(a[i]-b[j])+abs(b[j]-p);
}
bool check(ll x)
{
for(int i=1,j=1;i<=n;++i)
{
while(j<=k&&sum(i,j)>x)j++;
if(j>k)return 0;++j;
}
return 1;
}
int main()
{
#ifdef LOCAL
freopen("input.txt","r",stdin);
//    freopen("output.txt","w",stdout);
#endif // LOCAL

scanllddd(n,k,p);
R1(i,n)scanlld(a[i]);
R1(i,k)scanlld(b[i]);
sort(a+1,a+1+n);
sort(b+1,b+1+k);
ll ans = 2000000000;
ll l = 0 , r = 2000000000;
while(l<=r)
{
ll mid = (l+r)>>1;
if(check(mid))
{
r=mid-1;
ans = min(ans,mid);
}
else l=mid+1;
}
llans();
return 0;
}