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题目1：B. Vasya and Cornfield——https://codeforces.com/contest/1058/problem/B
AC代码：
#include <bits/stdc++.h>
using namespace std;
int main()
{
int n, d, m, ans;
int x1, y1, x2, y2, x3, y3, x4, y4;
int l1, l2, l3, l4;
double S, s1, s2, s3, s4, x, y;
while( ~scanf( "%d%d", &n, &d ) )
{
x1 = 0, y1 = d;
x2 = d, y2 = 0;
x3 = n, y3 = n - d;
x4 = n - d, y4 = n;
S = s1 = s2 = s3 = s4 = 0;
S = sqrt( ( x1 - x2 ) * ( x1 - x2 ) + ( y1 - y2 ) * ( y1 - y2 ) ) * sqrt( ( x2 - x3 ) * ( x2 - x3 ) + ( y2 - y3 ) * ( y2 - y3 ) );
scanf( "%d", &m );
for( int i = 0; i < m; i ++ )
{
scanf( "%lf%lf", &x, &y );
{
s1 = (double)( ( x1 - x ) * ( y2 - y ) - ( x2 - x ) * ( y1 - y ) ) / 2;
s2 = (double)( ( x2 - x ) * ( y3 - y ) - ( x3 - x ) * ( y2 - y ) ) / 2;
s3 = (double)( ( x3 - x ) * ( y4 - y ) - ( x4 - x ) * ( y3 - y ) ) / 2;
s4 = (double)( ( x4 - x ) * ( y1 - y ) - ( x1 - x ) * ( y4 - y ) ) / 2;
}
///printf( "s1 = %lf,\ts2 = %lf,\ts3 = %lf,\ts4 = %lf,\ts1 + s2 + s3 + s4 = %lf,\tabs(s1) + abs(s2) + abs(s3) + abs(s4) = %lf,\tS = %lf\n", s1, s2, s3, s4, s1 + s2 + s3 + s4, abs(s1) + abs(s2) + abs(s3) + abs(s4), S );
if( ( ( abs(s1) + abs(s2) + abs(s3) + abs(s4) ) - S ) / ( abs(s1) + abs(s2) + abs(s3) + abs(s4) ) <= 1e-5 ) ///精度要高一点，原来设置为 1e-2 就在第22个测试点WA了
printf( "YES\n" );
else
printf( "NO\n" );
}
}
return 0;
}
题目2：A. In Search of an Easy Problem——https://codeforces.com/contest/1030/problem/A
AC代码：
#include <bits/stdc++.h>
using namespace std;
int main()
{
int n, num;
bool flag;
while( ~scanf( "%d", &n ) )
{
flag = true;
for( int i = 0; i < n; i ++ )
{
scanf( "%d", &num );
if(num)
flag = false;
}
printf( "%s\n", flag ? "EASY" : "HARD" );
}
return 0;
}题目3：https://vjudge.net/contest/65959#problem/A
AC代码：
//#include <bits/stdc++.h>
#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;
const int maxn = 1e3 + 3;
int cnt, tot, n, k;
int vis[maxn];
char Str[maxn][maxn];
void dfs(int);
int main()
{
while( ~scanf( "%d%d", &n, &k ) && n != -1 && k != -1 )
{
cnt = tot = 0;
memset( vis, 0, sizeof(vis) );
/*
if( n == -1 && k == -1 )
break;
*/
for( int i = 1; i <= n; i ++ )
//scanf( "%s", Str[i] );
//cin >> Str[i];
for( int j = 1; j <= n; j ++ )
cin >> Str[i][j];
//scanf( "%c", &Str[i][j] );
dfs(1);
printf( "%d\n", tot );
}
return 0;
}
void dfs( int cur )
{
if( cnt == k )
{
tot ++;
return;
}
if( cur == n + 1 )
return;
for( int i = 1; i <= n; i ++ )
{
if( Str[cur][i] == '#' && !vis[i] )
{
cnt ++;
vis[i] = 1;
dfs( cur + 1 );
cnt --;
vis[i] = 0;
}
}
dfs( cur + 1 );
}题目5：https://vjudge.net/contest/65959#problem/B
AC代码：
//#include <bits/stdc++.h>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <malloc.h>
#include <iostream>
#include <algorithm>
#include <string>
#include <vector>
#include <queue>
#include <map>
using namespace std;
const int maxn = 33;
char Map[maxn][maxn][maxn];
bool vis[maxn][maxn][maxn];
int l, r, c;
bool flag = false;
struct node
{
int x, y, z, cnt;
node( int a, int b, int c, int d )
{
x = a;
y = b;
z = c;
cnt = d;
//x = a, y = b, z = c, cnt = d;
}
};
void dfs( int, int, int );
int main()
{
while( ~scanf( "%d%d%d", &l, &r, &c ) && l && c && r )
{
for( int i = 0; i < l; i ++ )
{
getchar();
for( int j = 0; j < r; j ++ )
{
fill( vis[i][j], vis[i][j] + c + 1, false );
gets(Map[i][j]);
//cin >> Map[i][j];
}
}
for( int i = 0; i < l; i ++ )
{
for( int j = 0; j < r; j ++ )
{
for( int k = 0; k < c; k ++ )
{
if( Map[i][j][k] == 'S' )
{
flag = false;
dfs( i, j, k );
break;
}
}
}
}
/*
for( int i = 0; i < l; i ++ )
{
for( int j = 0; j < r; j ++ )
{
for( int k = 0; k < c; k ++ )
{
cout<<Map[i][j][k];
}
cout << endl;
}
}
*/
if( !flag )
printf( "Trapped!\n" );
}
return 0;
}
void dfs( int x, int y, int z )
{
queue<node>q;
node start( x, y, z, 0 );
q.push(start);
while( !q.empty() )
{
node p = q.front();
q.pop();
if( p.x < l && p.x >= 0 && p.y >= 0 && p.y < r && p.z >= 0 && p.z < c )
{
if( Map[p.x][p.y][p.z] == 'E' )
{
flag = true;
printf( "Escaped in %d minute(s).\n", p.cnt );
break;
}
else if( Map[p.x][p.y][p.z] != '#' && !vis[p.x][p.y][p.z] )
{
vis[p.x][p.y][p.z] = true;
{
node tmp( p.x + 1, p.y, p.z, p.cnt + 1 );
q.push(tmp);
}
{
node tmp( p.x - 1, p.y, p.z, p.cnt + 1 );
q.push(tmp);
}
{
node tmp( p.x, p.y + 1, p.z, p.cnt + 1 );
q.push(tmp);
}
{
node tmp( p.x, p.y - 1, p.z, p.cnt + 1 );
q.push(tmp);
}
{
node tmp( p.x, p.y, p.z + 1, p.cnt + 1 );
q.push(tmp);
}
{
node tmp( p.x, p.y, p.z - 1, p.cnt + 1 );
q.push(tmp);
}
}
}
}
}题目6：https://vjudge.net/contest/65959#problem/C
AC代码：
//#include <bits/stdc++.h>
#include <cstdio>
#include <cstring>
#include <cstdlib>
//#include <malloc.h>
#include <iostream>
#include <algorithm>
#include <string>
#include <vector>
#include <queue>
#include <map>
using namespace std;
const int maxn = 1e6 + 13;
int dp[maxn];
bool vis[maxn];
int n, k;
int bfs( int, int );
int main()
{
while( ~scanf( "%d%d", &n, &k ) )
{
memset( vis, false, sizeof(vis) );
vis[n] = true;
/*
说法①：
就是入队的都是出现过的
n已经出现过了，不再入队了
说法②：
初始的点要标记已经走过，不然会重复经过
如果n=k，那么ans会变成2而不是0
*/
memset( dp, 0, sizeof(dp) );
printf( "%d\n", bfs( n, k ) );
}
return 0;
}
int bfs( int n, int m )
{
queue<int>q;
q.push(n);
int ans;
while( !q.empty() )
{
int tmp = q.front();
q.pop();
for( int i = 1; i <= 3; i ++ )
{
if( i == 1 )
ans = tmp - 1;
else if( i == 2 )
ans = tmp + 1;
else
ans = 2 * tmp;
if( ans < 0 || ans > maxn )
continue;
if( !vis[ans] )
{
vis[ans] = true;
dp[ans] = dp[tmp] + 1;
q.push(ans);
}
}
}
return dp[k];
}