SMU2017年校賽 題解
阿新 • • 發佈：2021-11-24
A.星圖
l[i],r[i],u[i],d[i]分別代表第\(i\)行或（列）從某個方向看過去的第一個黑洞所在位置
然後判斷對應的黑洞是否在當前點的後面
#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.好數
若存在大於等於兩個數，則必有一數與第一個數不相同
#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.裝進肚子
貪心，早上甜蜜值減去晚上甜蜜值，越大越適合早上吃
#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愛吃糖
字首和
#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.開心的塗刷
總方案數\(m^n\)，任意相鄰格子不同的方案數\(m\times(m-1)^{n-1}\)
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.兼職數靶
打個表就行
#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.卡牌遊戲
只記錄Alice比Bob多贏了幾局即可
#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!
簽到題輸入\(n\)輸出\(n\)個gu...和一句話，正式賽大家應該都是被英文勸退了吧
#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.快餓死的XzzF
動態規劃，記憶化搜尋也行吧
#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.小豬佩奇練打字
做個簡單的雜湊即可
#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.免費WIFI
貪心的選擇即可
似乎有優先佇列做法，我每次sort暴力跑也過了
#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;
}