【Codeforces】-615A-Bulbs(思维,模型:桶)
2016-07-22 08:57
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A. Bulbs
time limit per test
1 second
memory limit per test
256 megabytes
input
standard input
output
standard output
Vasya wants to turn on Christmas lights consisting of m bulbs. Initially, all bulbs are turned off. There are n buttons,
each of them is connected to some set of bulbs. Vasya can press any of these buttons. When the button is pressed, it turns on all the bulbs it's connected to. Can Vasya light up all the bulbs?
If Vasya presses the button such that some bulbs connected to it are already turned on, they do not change their state, i.e. remain turned on.
Input
The first line of the input contains integers n and m (1 ≤ n, m ≤ 100) —
the number of buttons and the number of bulbs respectively.
Each of the next n lines contains xi (0 ≤ xi ≤ m) —
the number of bulbs that are turned on by the i-th button, and then xi numbers yij(1 ≤ yij ≤ m) —
the numbers of these bulbs.
Output
If it's possible to turn on all m bulbs print "YES",
otherwise print "NO".
Examples
input
output
input
output
Note
In the first sample you can press each button once and turn on all the bulbs. In the 2 sample it is impossible to turn on the 3-rd lamp.
把按钮可以按亮的灯标记为1,循环判断已知灯里有没有0的,有就不可以。
#include<cstdio>
int main()
{
int n,m,z=1;
int a[110]={0},b[110];
scanf("%d %d",&n,&m);
for(int i=1;i<=n;i++)
{
scanf("%d",&b[i]);
while(b[i]--)
{
int x;
scanf("%d",&x);
a[x]=1;<span style="white-space:pre"> </span>//亮灯标记为1
}
}
for(int i=1;i<=m;i++)
{
if(a[i]==0)<span style="white-space:pre"> </span>//有不为1的即不亮,退出
{
z=0;<span style="white-space:pre"> </span>
break;
}
}
if(z)
printf("YES\n");
else
printf("NO\n");
return 0;
}
A. Bulbs
time limit per test
1 second
memory limit per test
256 megabytes
input
standard input
output
standard output
Vasya wants to turn on Christmas lights consisting of m bulbs. Initially, all bulbs are turned off. There are n buttons,
each of them is connected to some set of bulbs. Vasya can press any of these buttons. When the button is pressed, it turns on all the bulbs it's connected to. Can Vasya light up all the bulbs?
If Vasya presses the button such that some bulbs connected to it are already turned on, they do not change their state, i.e. remain turned on.
Input
The first line of the input contains integers n and m (1 ≤ n, m ≤ 100) —
the number of buttons and the number of bulbs respectively.
Each of the next n lines contains xi (0 ≤ xi ≤ m) —
the number of bulbs that are turned on by the i-th button, and then xi numbers yij(1 ≤ yij ≤ m) —
the numbers of these bulbs.
Output
If it's possible to turn on all m bulbs print "YES",
otherwise print "NO".
Examples
input
3 4 2 1 4 3 1 3 1 1 2
output
YES
input
3 3 1 1 1 2 1 1
output
NO
Note
In the first sample you can press each button once and turn on all the bulbs. In the 2 sample it is impossible to turn on the 3-rd lamp.
把按钮可以按亮的灯标记为1,循环判断已知灯里有没有0的,有就不可以。
#include<cstdio>
int main()
{
int n,m,z=1;
int a[110]={0},b[110];
scanf("%d %d",&n,&m);
for(int i=1;i<=n;i++)
{
scanf("%d",&b[i]);
while(b[i]--)
{
int x;
scanf("%d",&x);
a[x]=1;<span style="white-space:pre"> </span>//亮灯标记为1
}
}
for(int i=1;i<=m;i++)
{
if(a[i]==0)<span style="white-space:pre"> </span>//有不为1的即不亮,退出
{
z=0;<span style="white-space:pre"> </span>
break;
}
}
if(z)
printf("YES\n");
else
printf("NO\n");
return 0;
}
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