Codeforces Round #459 (Div. 2)总结

争取一场上蓝（flag）！

flag炸了，不仅没上蓝，还掉分了。

Codeforces Round #459 (Div. 2)

A：傻逼模拟

AC代码：

#include <iostream>
#include <cstdio>
#include <map>
const int MAXN = 100000 ;
using namespace std ;

inline int read ( ) {
int x = 0 , w = 1 ; char c = ' ' ;
while ( c < '0' || c > '9' ) { c = getchar ( ) ; if ( c == '-' ) w = -1 ; }
while ( c >= '0' && c <= '9' ) x = ( x << 1 ) + ( x << 3 ) + ( c ^ 48 ) , c = getchar ( ) ;
return x * w ;
}

map < int , bool > H ;

int f[MAXN + 5] ;

int main ( ) {
int n = read ( ) ;

f[1] = 1 , f[2] = 1 ; H[1] = true ;

int i = 3 ;

while ( f[i - 1 ] <= 1000 )
f[i] = f[i - 1] + f[i - 2] , H[f[i]] = true , ++i ;

for ( int i = 1 ; i <= n ; ++i )
if ( H[i] ) cout << 'O' ; else cout << 'o' ;

return 0 ;
}

B：傻逼模拟

AC代码：

#include <iostream>
#include <cstdio>
#include <map>
const int MAXN = 100000 ;
using namespace std ;

inline int read ( ) {
int x = 0 , w = 1 ; char c = ' ' ;
while ( c < '0' || c > '9' ) { c = getchar ( ) ; if ( c == '-' ) w = -1 ; }
while ( c >= '0' && c <= '9' ) x = ( x << 1 ) + ( x << 3 ) + ( c ^ 48 ) , c = getchar ( ) ;
return x * w ;
}

map < string , string > H ;

int main ( ) {
int n = read ( ) , m = read ( ) ;
for ( int i = 1 ; i <= n ; ++i ) {
string str , ip ;
cin >> str >> ip ;
ip += ";" ;
H[ip] = str ;
}
for ( int i = 1 ; i <= m ; ++i ) {
string str , ip ;
cin >> str >> ip ;
cout << str << ' ' << ip << " #" << H[ip] << endl ;
}
return 0 ;
}

C：看到觉得是DP，写了个记忆化，炸了。

后来发现看错题了，求的是区间。所以大框架肯定是O（n^2），然后用奇怪的技巧算能否匹配。看起来有点像区间DP，但我还是不会orz

D：CF居然有博弈。我看完了题，先想了想博弈搜索，发现不会先，又觉得是记忆化。结果样例过不了orz。这题感觉有点像“传纸条”。看了题解真的是记忆化!思路也是对的。我的码力真是太差了orz。考后终于调出来。

AC代码

#include <iostream>
#include <cstdio>
#include <cstring>
const int MAXN = 100 ;
const int INF = 0x3f3f3f3f ;
using namespace std ;

inline int read ( ) {
int x = 0 , w = 1 ; char c = ' ' ;
while ( c < '0' || c > '9' ) { c = getchar ( ) ; if ( c == '-' ) w = -1 ; }
while ( c >= '0' && c <= '9' ) x = ( x << 1 ) + ( x << 3 ) + ( c ^ 48 ) , c = getchar ( ) ;
return x * w ;
}

struct Node {
int to , w , nxt ;
} edge[MAXN * MAXN + 5] ;

bool flag ;

class Graph {
public :
Graph ( ) { memset ( head , -1 , sizeof ( head ) ) , tot = 0 ; memset  ( dp , -1 , sizeof ( dp ) ) ; }
void add ( int u , int v , int w ) ;
bool dfs ( int x , int y , int turn , int last ) ;
private :
int tot , head[MAXN + 5] , dp[MAXN + 5][MAXN + 5][3][27] ;
} G ;

void Graph :: add ( int u , int v , int w ) {
edge[tot] = ( Node ) { v , w , head[u] } , head[u] = tot++ ;
}

bool Graph :: dfs ( int x , int y , int turn , int last ) {
if ( dp[x][y][turn][last] != -1 ) return dp[x][y][turn][last] ;

int flag = false ;

if ( !turn )
for ( int i = head[x] ; ~i ; i = edge[i].nxt ) {
int v = edge[i].to , w = edge[i].w ;
if ( w >= last ) flag |= !dfs ( v , y , !turn , w ) ;
}
else
for ( int i = head[y] ; ~i ; i = edge[i].nxt ) {
int v = edge[i].to , w = edge[i].w ;
if ( w >= last ) flag |= !dfs ( x , v , !turn , w ) ;
}

dp[x][y][turn][last] = flag ;

return dp[x][y][turn][last] ;
}

int main ( ) {
int n = read ( ) , e = read ( ) ;

for  ( int i = 1 ; i <= e ; ++i ) {
int u = read ( ) , v = read ( ) ;
char c ; cin >> c ;
G.add ( u , v , c - 'a' ) ;
}

for ( int i = 1 ; i <= n ; ++i ) {
for ( int j = 1 ; j <= n ; ++j ) {
flag = G.dfs ( i , j , 0 , -1 ) ;
if ( flag ) cout << 'A' ; else cout << 'B' ;
}
cout << endl ;
}

return 0 ;
}