CF 292C Beautiful IP Addresses

 

Question:

Croc's first round in 2013, so it's hard to do it at night...

After a simple analysis of the meaning, we can find that if n> = 7, there must be no solution, because each value is different and must be used once. In addition, it must meet the requirements of the reply, assuming n = 7, then the minimum length is 6 + 1 + 6 = 13> 12, so n> = 7 is certainly unsolvable.

Therefore, the deep search brute-force method is used to obtain all the input strings. The number of input strings does not exceed 2*6 ^ 6 (n <= 6). In each input string, add 'to each input string '. 'To form an IP address, so the maximum number of operations is 27*2*6 ^ 6 = 2519424 (certainly far smaller than this number), and the ip address must be removed. is still the original return string, otherwise there will be duplicates and errors.

 

Code:

[Cpp]
# Include <stdlib. h>
# Include <string. h>
# Include <stdio. h>
# Include <ctype. h>
# Include <math. h>
# Include <stack>
# Include <queue>
# Include <map>
# Include <set>
# Include <vector>
# Include <string>
# Include <iostream>
# Include <algorithm>
Using namespace std;
 
# Define ll _ int64
# Define ls rt <1
# Define rs ls | 1
# Define lson l, mid, ls
# Define rson mid + 1, r, rs
# Define middle (l + r)> 1
# Define clr_all (x, c) memset (x, c, sizeof (x ))
# Define clr (x, c, n) memset (x, c, sizeof (x [0]) * (n + 1 ))
# Define eps (1e-8)
# Define MOD 1000000007.
# Define INF 0x3f3f3f
# Define PI (acos (-1.0 ))
# Pragma comment (linker, "/STACK: 102400000,102400000 ")
Template <class T> T _ max (T x, T y) {return x> y? X: y ;}
Template <class T> T _ min (T x, T y) {return x <y? X: y ;}
Template <class T> T _ abs (T x) {return (x <0 )? -X: x ;}
Template <class T> T _ mod (T x, T y) {return (x> 0 )? X % y :( (x % y) + y) % y ;}
Template <class T> void _ swap (T & x, T & y) {T t = x; x = y; y = t ;}
Template <class T> void getmax (T & x, T y) {x = (y> x )? Y: x ;}
Template <class T> void getmin (T & x, T y) {x = (x <0 | y <x )? Y: x ;}
Int TS, cas = 1;
Const int M = 100000 + 5;
Int n, a [11];
Int vis [11], cnt, tot;
Struct ip {
Int a, B, c, d;
Ip (int _ a = 0, int _ B = 0, int _ c = 0, int _ d = 0) {a = _ a, B = _ B, c = _ c, d = _ d ;}
Void show () {printf ("% d. % d \ n", a, B, c, d );}
};
Struct node {
Int a [22], len;
Void show () {for (int I = 1; I <= len; I ++) printf ("% d", a [I]); puts ("");}
} Tmp;
Vector <ip> ret;
Vector <node> pal;
 
Bool check (int & num, int len, int cur, int p ){
Num = 0;
For (int I = 1; I <= len; I ++) num * = 10, num + = pal [p]. a [cur ++];
If (num> 255 | (num! = 0 & pal [p]. a [cur-len] = 0) | (num = 0 & len! = 1 ))
Return false;
Return true;
}
 
Void addToRet (int p ){
Int I, j, k, l, cur;
Ip t;
For (I = 1; I <= 3; I ++) if (pal [p]. len-I <= 9 ){
If (pal [p]. len-I <3 | pal [p]. len <I + 3) break;
If (! Check (t. a, I, 1, p) continue;
For (j = 1; j <= 3; j ++) if (pal [p]. len-I-j <= 6 ){
If (pal [p]. len-I-j <2 | pal [p]. len <I + j + 2) break;
If (! Check (t. B, j, I + 1, p) continue;
For (k = 1; k <= 3; k ++) if (pal [p]. len-I-j-k <= 3 ){
If (pal [p]. len-I-j-k <1 | pal [p]. len <I + j + k + 1) break;
If (! Check (t. c, k, I + j + 1, p) continue;
L = pal [p]. len-I-j-k;
If (! Check (t. d, l, I + j + k + 1, p) continue;
Ret. push_back (t );
}
}
}
}
 
Void dfs (int p ){
Int I;
If (p> tot ){
If (cnt = n ){
Tmp. len = (tot <1 );
For (I = tot + 1; I <= tmp. len; I ++)
Tmp. a [I] = tmp. a [tmp. len-I + 1];
Pal. push_back (tmp );
If (tot + tot-1> = 4 ){
Tmp. len-= 1;
For (I = tot + 1; I <= tmp. len; I ++)
Tmp. a [I] = tmp. a [tmp. len-I + 1];
Pal. push_back (tmp );
}
}
Return;
}
For (I = 1; I <= n; I ++ ){
If (! Vis [I]) cnt ++;
Vis [I] ++;
Tmp. a [p] = a [I], dfs (p + 1 );
Vis [I] --;
If (! Vis [I]) cnt --;
}
}
 
Void run (){
Int I, j;
For (I = 1; I <= n; I ++)
Scanf ("% d", & a [I]);
Clr_all (vis, 0), cnt = 0;
Ret. clear (), pal. clear ();
For (tot = 2; tot <= 6; tot ++) if (tot> = n) dfs (1 );
For (I = 0; I <pal. size (); I ++) addToRet (I );
Printf ("% d \ n", ret. size ());
For (I = 0; I <ret. size (); I ++) ret [I]. show ();
}
 
Void preSof (){
}
 
Int main (){
// Freopen ("input.txt", "r", stdin );
// Freopen ("output.txt", "w", stdout );
PreSof ();
// Run ();
While ((~ Scanf ("% d", & n) run ();
// For (scanf ("% d", & TS); cas <= TS; cas ++) run ();
Return 0;
}

# Include <stdlib. h>
# Include <string. h>
# Include <stdio. h>
# Include <ctype. h>
# Include <math. h>
# Include <stack>
# Include <queue>
# Include <map>
# Include <set>
# Include <vector>
# Include <string>
# Include <iostream>
# Include <algorithm>
Using namespace std;

# Define ll _ int64
# Define ls rt <1
# Define rs ls | 1
# Define lson l, mid, ls
# Define rson mid + 1, r, rs
# Define middle (l + r)> 1
# Define clr_all (x, c) memset (x, c, sizeof (x ))
# Define clr (x, c, n) memset (x, c, sizeof (x [0]) * (n + 1 ))
# Define eps (1e-8)
# Define MOD 1000000007.
# Define INF 0x3f3f3f
# Define PI (acos (-1.0 ))
# Pragma comment (linker, "/STACK: 102400000,102400000 ")
Template <class T> T _ max (T x, T y) {return x> y? X: y ;}
Template <class T> T _ min (T x, T y) {return x <y? X: y ;}
Template <class T> T _ abs (T x) {return (x <0 )? -X: x ;}
Template <class T> T _ mod (T x, T y) {return (x> 0 )? X % y :( (x % y) + y) % y ;}
Template <class T> void _ swap (T & x, T & y) {T t = x; x = y; y = t ;}
Template <class T> void getmax (T & x, T y) {x = (y> x )? Y: x ;}
Template <class T> void getmin (T & x, T y) {x = (x <0 | y <x )? Y: x ;}
Int TS, cas = 1;
Const int M = 100000 + 5;
Int n, a [11];
Int vis [11], cnt, tot;
Struct ip {
Int a, B, c, d;
Ip (int _ a = 0, int _ B = 0, int _ c = 0, int _ d = 0) {a = _ a, B = _ B, c = _ c, d = _ d ;}
Void show () {printf ("% d. % d \ n", a, B, c, d );}
};
Struct node {
Int a [22], len;
Void show () {for (int I = 1; I <= len; I ++) printf ("% d", a [I]); puts ("");}
} Tmp;
Vector <ip> ret;
Vector <node> pal;

Bool check (int & num, int len, int cur, int p ){
Num = 0;
For (int I = 1; I <= len; I ++) num * = 10, num + = pal [p]. a [cur ++];
If (num> 255 | (num! = 0 & pal [p]. a [cur-len] = 0) | (num = 0 & len! = 1 ))
Return false;
Return true;
}

Void addToRet (int p ){
Int I, j, k, l, cur;
Ip t;
For (I = 1; I <= 3; I ++) if (pal [p]. len-I <= 9 ){
If (pal [p]. len-I <3 | pal [p]. len <I + 3) break;
If (! Check (t. a, I, 1, p) continue;
For (j = 1; j <= 3; j ++) if (pal [p]. len-I-j <= 6 ){
If (pal [p]. len-I-j <2 | pal [p]. len <I + j + 2) break;
If (! Check (t. B, j, I + 1, p) continue;
For (k = 1; k <= 3; k ++) if (pal [p]. len-I-j-k <= 3 ){
If (pal [p]. len-I-j-k <1 | pal [p]. len <I + j + k + 1) break;
If (! Check (t. c, k, I + j + 1, p) continue;
L = pal [p]. len-I-j-k;
If (! Check (t. d, l, I + j + k + 1, p) continue;
Ret. push_back (t );
}
}
}
}

Void dfs (int p ){
Int I;
If (p> tot ){
If (cnt = n ){
Tmp. len = (tot <1 );
For (I = tot + 1; I <= tmp. len; I ++)
Tmp. a [I] = tmp. a [tmp. len-I + 1];
Pal. push_back (tmp );
If (tot + tot-1> = 4 ){
Tmp. len-= 1;
For (I = tot + 1; I <= tmp. len; I ++)
Tmp. a [I] = tmp. a [tmp. len-I + 1];
Pal. push_back (tmp );
}
}
Return;
}
For (I = 1; I <= n; I ++ ){
If (! Vis [I]) cnt ++;
Vis [I] ++;
Tmp. a [p] = a [I], dfs (p + 1 );
Vis [I] --;
If (! Vis [I]) cnt --;
}
}

Void run (){
Int I, j;
For (I = 1; I <= n; I ++)
Scanf ("% d", & a [I]);
Clr_all (vis, 0), cnt = 0;
Ret. clear (), pal. clear ();
For (tot = 2; tot <= 6; tot ++) if (tot> = n) dfs (1 );
For (I = 0; I <pal. size (); I ++) addToRet (I );
Printf ("% d \ n", ret. size ());
For (I = 0; I <ret. size (); I ++) ret [I]. show ();
}

Void preSof (){
}

Int main (){
// Freopen ("input.txt", "r", stdin );
// Freopen ("output.txt", "w", stdout );
PreSof ();
// Run ();
While ((~ Scanf ("% d", & n) run ();
// For (scanf ("% d", & TS); cas <= TS; cas ++) run ();
Return 0;
}