Codeforces Round #615 (Div. 3)B. Collecting Packages

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概述

There is a robot in a warehouse and n packages he wants to collect. The warehouse can be represented as a coordinate grid. Initially, the robot stays at the point (0,0). The i-th package is at the point (xi,yi). It is guaranteed that there are no two packages at the same point. It is also guaranteed that the point (0,0)

doesn't contain a package.

The robot is semi-broken and only can move up ('U') and right ('R'). In other words, in one move the robot can go from the point (x,y)

to the point (x+1,y) or to the point (x,y+1)

As we say above, the robot wants to collect all n

packages (in arbitrary order). He wants to do it with the minimum possible number of moves. If there are several possible traversals, the robot wants to choose the lexicographically smallest path.

The string s

of length n is lexicographically less than the string t of length n if there is some index 1≤j≤n that for all i from 1 to j−1 si=ti and sj<tj

. It is the standard comparison of string, like in a dictionary. Most programming languages compare strings in this way.

Input

The first line of the input contains an integer t

(1≤t≤100

) — the number of test cases. Then test cases follow.

The first line of a test case contains one integer n

(1≤n≤1000

) — the number of packages.

The next n

lines contain descriptions of packages. The i-th package is given as two integers xi and yi (0≤xi,yi≤1000) — the x-coordinate of the package and the y

-coordinate of the package.

It is guaranteed that there are no two packages at the same point. It is also guaranteed that the point (0,0)

doesn't contain a package.

The sum of all values n

over test cases in the test doesn't exceed 1000

Output

Print the answer for each test case.

If it is impossible to collect all n

packages in some order starting from (0,0

), print "NO" on the first line.

Otherwise, print "YES" in the first line. Then print the shortest path — a string consisting of characters 'R' and 'U'. Among all such paths choose the lexicographically smallest path.

Note that in this problem "YES" and "NO" can be only uppercase words, i.e. "Yes", "no" and "YeS" are not acceptable.

Example

Input

Copy

Output

Copy

YES
RUUURRRRUU
NO
YES
RRRRUUU

Note

For the first test case in the example the optimal path RUUURRRRUU is shown below:

思路：如果某个点比它前一个点的x或y坐标小的话NO；

#include<iostream>
#include<cstring>
#include<algorithm>
using namespace std;
int t,n;
struct T{
int x;
int y;
}mp[1010];
bool cmp(T u,T v)
{
if(u.x==v.x)
return u.y<v.y;
return u.x<v.x;
}
string s;
int solve()
{
s="";
for(int i=1;i<=n;i++)
{
int a=mp[i].x-mp[i-1].x;
int b=mp[i].y-mp[i-1].y;
if(a<0||b<0)
return 0;
else
{
while(a--) s+='R';
while(b--) s+='U';
}
}
return 1;
}
int main()
{
mp[0].x=0;
mp[0].y=0;
cin>>t;
while(t--)
{
cin>>n;
for(int i=1;i<=n;i++)
cin>>mp[i].x>>mp[i].y;
sort(mp+1,mp+n+1,cmp);
if(!solve()) cout<<"NO"<<endl;
else cout<<"YES"<<endl<<s<<endl;
}
return 0;
}