Poj 3740 easy finding DLX

Question: Give You A 0, 1 matrix for exact coverage

Solution:

DLX

Solution code:

1 // file name: poj3740.cpp 2 // Author: darkdream 3 // created time: saturday, October 04, 2014, 31 seconds, 4 5 # include <vector> 6 # include <list> 7 # include <map> 8 # include <set> 9 # include <deque> 10 # include <stack> 11 # include <bitset> 12 # include <algorithm> 13 # include <functional> 14 # include <numeric> 15 # include <utility> 16 # include <sstream> 17 # include <iostream> 18 # include <iomanip> 19 # include <cstdio> 20 # I Nclude <cmath> 21 # include <cstdlib> 22 # include <cstring> 23 # include <ctime> 24 # define ll long 25 26 using namespace STD; 27 const int maxnode = 50000; 28 const int maxn = 18; 29 const int maxm = 400; 30 struct DLX 31 {32 int n, m, size; 33 int U [maxnode], d [maxnode], L [maxnode], R [maxnode], row [maxnode], Col [maxnode]; 34 int H [maxn], s [maxm]; 35 void Init (INT _ n, int _ m) 36 {37 n = _ n; 38 m = _ m; 39 for (INT I = 0; I <= m; I ++) 40 {41 s [I] = 0; 42 U [I] = I; 43 d [I] = I; 44 L [I] = I-1; 45 R [I] = I + 1; 46} 47 size = m; 48 L [0] = m; 49 R [m] = 0; 50 memset (H,-1, sizeof (h); 51} 52 void Link (int r, int c) 53 {54 + + s [col [++ size] = C]; 55 row [size] = r; 56 d [size] = d [c]; 57 U [d [c] = size; 58 U [size] = C; 59 d [c] = size; 60 if (H [R] <0) H [R] = L [size] = R [size] = size; 61 else {62 R [siz E] = R [H [R]; 63 l [R [H [R] = size; 64 L [size] = H [R]; 65 R [H [R] = size; 66} 67} 68 void remove (INT c) 69 {70 L [R [c] = L [c]; 71 R [L [c] = R [c]; 72 for (INT I = d [c]; I! = C; I = d [I]) 73 for (Int J = R [I]; J! = I; j = R [J]) 74 {75 U [d [J] = U [J]; 76 d [U [J] = d [J]; 77 -- s [col [J]; 78} 79} 80 void resume (INT c) 81 {82 L [R [c] = C; 83 R [L [c] = C; 84 For (INT I = d [c]; I! = C; I = d [I]) 85 for (Int J = R [I]; J! = I; j = R [J]) 86 {87 U [d [J] = J; 88 d [U [J] = J; 89 + + s [col [J]; 90} 91} 92 bool Dance () 93 {94 If (R [0] = 0) 95 {96 return true; 97} 98 int c = R [0]; 99 for (INT I = R [c]; I! = 0; I = R [I]) 100 if (s [I] <s [c]) 101 C = I; 102 remove (C ); 103 for (INT I = d [c]; I! = C; I = d [I]) 104 {105 for (Int J = R [I]; J! = I; j = R [J]) Remove (COL [J]); 106 If (Dance () return true; 107 for (Int J = R [I]; j! = I; j = R [J]) Resume (COL [J]); 108} 109 resume (c); 110 return false; 111} 112}; 113 114 DLX g; 115 int main () {116 int n, m; 117 while (scanf ("% d", & N, & M )! = EOF) 118 {119G. init (n, m); 120 int t; 121 for (INT I = 1; I <= N; I ++) 122 for (Int J = 1; j <= m; j ++) 123 {124 scanf ("% d", & T); 125 If (t) 126G. link (I, j); 127} 128 If (G. dance () 129 printf ("Yes, I found it \ n"); 130 else printf ("It is impossible \ n"); 131} 132 return 0; 133}

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Poj 3740 easy finding DLX