Uvaoj10054-The neck.pdf

1/* 2 Question: print the Euler loop! 3. Why is DFS a post-sequential traversal? 4 because the Euler Loop itself is a loop, we may find a loop in advance during DFS. This loop may not be an Euler loop. 5 because it has not traversed all the sides! If it is written as a forward traversal, the stored path is not a complete path! It may consist of multiple circuits! The answer is wrong! If it is post-sequential traversal, when DFS encounters a loop, it will exit the search of the current stack! 7. Search for other paths! Only one loop path is obtained! --> Euler Loop ~! 8 */9 # include <iostream> 10 # include <cstring> 11 # define M 5512 # define Max 0x3f3f3f13 using namespace STD; 14 15 int CNT [m] [m]; 16 int deg [m]; 17 int map [m] [m]; 18 int X; 19 20 struct point {21 int X, Y; 22 point () {} 23 24 point (int x, int y) {25 this-> X = x; 26 This-> Y = y; 27} 28 }; 29 30 point P [1005]; 31 int top; 32 33 void DFS (int u) {34 if (! DEG [u]) return; 35 for (INT I = 1; I <= 50; ++ I) 36 IF (Map [u] [I] & CNT [u] [I]) {37 -- CNT [u] [I]; 38 -- CNT [I] [u]; 39 -- deg [u]; 40 -- deg [I]; 41 DFS (I ); 42 p [++ top] = point (u, I); 43} 44} 45 46 int main () {47 int t, n, k = 0; 48 CIN> T; 49 while (t --) {50 CIN> N; 51 X = max; 52 memset (CNT, 0, sizeof (CNT )); 53 memset (MAP, 0, sizeof (MAP); 54 memset (deg, 0, sizeof (DEG); 55 for (INT I = 1; I <= N; ++ I) {56 int U, V; 57 CIN> U> V; 58 deg [u] ++; 59 deg [v] ++; 60 map [u] [v] = 1; 61 map [v] [u] = 1; 62 CNT [u] [v] ++; 63 CNT [v] [u] ++; 64 if (x> U) x = u; 65 if (x> V) X = V; 66} 67 int OK = 0; 68 for (INT I = 1; I <= 50; ++ I) 69 If (deg [I] % 2! = 0) {70 OK = 1; 71 break; 72} 73 cout <"case #" <+ + k <Endl; 74 if (OK) {75 cout <"some beads may be lost" <Endl; 76 if (t) cout <Endl; 77 continue; 78} 79 Top = 0; 80 DFS (x); 81 If (Top = N) {82 For (top; top> = 1; -- top) 83 cout <p [Top]. x <"" <p [Top]. Y <Endl; 84} 85 else cout <"some beads may be lost" <Endl; 86 If (t) cout <Endl; 87} 88 return 0; 89}