SMU2017年校赛 题解
A.星图
l[i],r[i],u[i],d[i]分别代表第\(i\)行或（列）从某个方向看过去的第一个黑洞所在位置
然后判断对应的黑洞是否在当前点的后面
#include <bits/stdc++.h>
using namespace std;
const int N = 1005;
int n , m , q , l[N] , r[N] , d[N] , u[N] ;
char mp[N][N];
inline int read()
{
int x = 0 , ch = getchar();
while( ch < '0' || ch > '9' ) ch = getchar();
while( ch >= '0' && ch <= '9' ) x = ( x << 3 ) + ( x << 1 ) + ch - '0' , ch = getchar();
return x;
}
int main()
{
n = read() , m = read() , q = read();
memset( u , 0x3f3f3f3f , sizeof(u) ) , memset( l , 0x3f3f3f3f , sizeof( l ) );
for( int i = 1 , f ; i <= n ; i ++ )
{
f = 1 ;
scanf( "%s" , mp[i] + 1 );
for( int j = 1 ; j <= m ; j ++ )
{
if( mp[i][j] == '#' )
{
if(f) f = 0 , l[i] = j;
r[i] = j;
d[j] = i;
}
}
}
for( int j = 1 ; j <= m ; j ++ )
{
for( int i = 1 ; i <= n ; i ++ )
{
if( mp[i][j] == '#' )
{
u[j] = i;
break;
}
}
}
int x , y ;
char dir;
for( int i = 1 ; i <= q ; i ++ )
{
x = read() , y = read() , scanf( "%c" , &dir );
if( dir == 'L' ) puts( l[x] > y ? "YES" : "NO" );
else if( dir == 'R' ) puts( r[x] < y ? "YES" : "NO" );
else if( dir == 'D' ) puts( d[y] < x ? "YES" : "NO" );
else puts( u[y] > x ? "YES" : "NO" );
}
return 0;
}
B.好数
若存在大于等于两个数，则必有一数与第一个数不相同
#include <bits/stdc++.h>
using namespace std;
int main()
{
string s;
cin >> s;
for( auto it : s )
{
if( it != s[0] )
{
cout << "NO";
exit(0);
}
}
cout << "YES\n";
}
C.装进肚子
贪心，早上甜蜜值减去晚上甜蜜值，越大越适合早上吃
#include <bits/stdc++.h>
using namespace std;
const int N = 100005;
int n , k ;
long long ans;
struct Node
{
int x , y;
friend bool operator < ( Node a , Node b ) { return a.x - a.y > b.x - b.y; }
} a[N];
int read()
{
int x = 0 , ch = getchar();
while( ch < '0' || ch > '9' ) ch = getchar();
while( ch >= '0' && ch <= '9' ) x = ( x << 3 ) + ( x << 1 ) + ch - '0' , ch = getchar();
return x;
}
int main()
{
n = read() , k = read();
for( int i = 1 ; i <= n ; i ++ ) a[i].x = read();
for( int i = 1 ; i <= n ; i ++ ) a[i].y = read();
sort( a + 1 , a + 1 + n );
for( int i = 1 ; i <= k ; i ++ ) ans += a[i].x;
for( int i = k + 1 ; i <= n ; i ++ ) ans += a[i].y;
cout << ans << endl;
}
D.ZZZZone爱吃糖
前缀和
#include <bits/stdc++.h>
using namespace std;
long long n , a[10005] , m , ans;
int main()
{
cin >> n;
for( int i = 1 ; i <= n ; i ++ ) cin >> a[i] , a[i] += a[ i - 1 ];
cin >> m;
for( int i = 1 , l , r ; i <= m ; i ++ )
{
cin >> l >> r;
ans += max( 0LL , a[r] - a[ l - 1 ] );
}
cout << ans << endl;
return 0;
}
E.开心的涂刷
总方案数\(m^n\)，任意相邻格子不同的方案数\(m\times(m-1)^{n-1}\)
作差
#include<bits/stdc++.h>
#define ll long long
using namespace std;
const ll mod = 1000000007;
ll n , m ;
ll ksm( ll x , ll y )
{
ll res = 1;
while( y )
{
if( y & 1 ) res = ( res * x ) % mod;
y >>= 1;
x = ( x * x ) % mod;
}
return res;
}
int main()
{
cin >> n >> m ;
m %= mod;
cout << ( ksm( m , n ) - m * ksm( m - 1 , n - 1 ) % mod + mod ) % mod << endl;
return 0;
}
F.兼职数靶
打个表就行
#include<bits/stdc++.h>
using namespace std;
int n , cnt;
int point[20][20] = { {1,1,1,1,1,1,1,1,1,1,1,1,1},
{1,2,2,2,2,2,2,2,2,2,2,2,1},
{1,2,2,2,2,2,2,2,2,2,2,2,1},
{1,2,2,3,3,3,3,3,3,3,2,2,1},
{1,2,2,3,3,3,3,3,3,3,2,2,1},
{1,2,2,3,3,4,4,4,3,3,2,2,1},
{1,2,2,3,3,4,4,4,3,3,2,2,1},
{1,2,2,3,3,4,4,4,3,3,2,2,1},
{1,2,2,3,3,3,3,3,3,3,2,2,1},
{1,2,2,3,3,3,3,3,3,3,2,2,1},
{1,2,2,2,2,2,2,2,2,2,2,2,1},
{1,2,2,2,2,2,2,2,2,2,2,2,1},
{1,1,1,1,1,1,1,1,1,1,1,1,1} };
bool get()
{
char ch = getchar();
while( ch != '.' && ch != '#' ) ch = getchar();
return ( ch == '#' ? 1 : 0 );
}
int main()
{
for( ; ; )
{
cin >> n;
if( n == 0 ) exit(0);
cnt = 0;
for( int i = 1 ; i <= 13 ; i ++ )
{
for( int j = 1 ; j <= 13 ; j ++ )
if( get() ) cnt += point[ i - 1 ][ j - 1 ];
}
printf( "%.2lf\n" , 1.0 * cnt / n );
}
return 0;
}
G.卡牌游戏
只记录Alice比Bob多赢了几局即可
#include <bits/stdc++.h>
using namespace std;
int n , t;
string a , b;
int main()
{
cin >> n;
for( int i = 1 ; i <= n ; i ++ )
{
cin >> a >> b;
if( ( a == "Jin" && b == "Mu" ) || ( a == "Mu" && b == "Tu" ) || ( a == "Tu" && b == "Shui" ) || ( a == "Shui" && b == "Huo" ) || ( a == "Huo" && b == "Jin" ) ) t ++;
if( ( b == "Jin" && a == "Mu" ) || ( b == "Mu" && a == "Tu" ) || ( b == "Tu" && a == "Shui" ) || ( b == "Shui" && a == "Huo" ) || ( b == "Huo" && a == "Jin" ) ) t --;
}
if( t > 0 ) cout << "Alice\n";
else if( t < 0 ) cout << "Bob\n";
else cout << "Draw\n";
return 0;
}
H.Hungry!
签到题输入\(n\)输出\(n\)个gu...和一句话，正式赛大家应该都是被英文劝退了吧
#include<bits/stdc++.h>
using namespace std;
int m;
string s;
unordered_map< char , char > h;
int main()
{
while(cin>>m)
{
for( int i = 1 ; i <= m ; i ++ ) cout << "gu...";
cout<< "\nThe story is so boring. And I am so hungry!\n";
}
}
I.快饿死的XzzF
动态规划，记忆化搜索也行吧
#include <bits/stdc++.h>
using namespace std;
int n ;
long long f[25][2];
int main()
{
cin >> n;
f[1][0] = f[1][1] = 1;
for( int i = 2 ; i <= n ; i ++ ) f[i][1] = f[i-1][0] + f[i-1][1] , f[i][0] = f[i-1][1];
cout << f[n][0] + f[n][1] << endl;
return 0;
}
J.小猪佩奇练打字
做个简单的哈希即可
#include<bits/stdc++.h>
using namespace std;
int m;
string s;
unordered_map< char , char > h;
int main()
{
cin >> s;
for( char i = 'a' ; i <= 'z' ; i ++ ) h[i] = i;
cin >> m;
for( char x , y ; m ; m -- )
{
cin >> x >> y;
swap( h[x] , h[y] );
}
for( auto i : s ) cout << h[i];
return 0;
}
K.免费WIFI
贪心的选择即可
似乎有优先队列做法，我每次sort暴力跑也过了
#include<bits/stdc++.h>
#define l first
#define r second
using namespace std;
long long q[10005] , n , cnt = 1 , m;
pair< long , long > t[10005];
int main()
{
cin >> n >> m;
for( int i = 1 ; i <= n ; i ++ ) cin >> t[i].l >> t[i].r;
sort( t + 1 , t + 1 + n );
for( int i = 1 , f ; i <= n ; i ++ )
{
f = 0;
for( int j = 1 ; j <= cnt && !f ; j ++ ) if( t[i].l > q[j] ) q[j] = t[i].r , f = 1;
if( !f ) q[ ++ cnt ] = t[i].r;
sort( q + 1 , q + 1 + cnt );
}
cout << cnt / m + ( cnt % m ? 1 : 0 ) << endl;
return 0;
}
