Advertisement poj-1752 **

1 /*
2 * a natural differential constraint system. If there is no specific write, convert it to one ..
3 *
4 *
5 * http://www.cnblogs.com/ihainan/archive/2011/07/23/2114884.html
6 * solution: the following constraints are available for the question:
7 *IfB-A> = K
8 *ThenS [B]-s [a]> = K
9 *OtherwiseS [B]-s [a]> = DIS (A, B)
10 *AndS [B]-s [a] <= DIS (A, B)
11 *At the same time0 <= s [I]-s [I-1] <= 1
12 *
13 * a graph can be created based on constraints. spfa calculates the longest path.
14 *
15 * it is better not to use things in STL. The written spfa is even slower than Bellman !!!
16 */
17
18 # include <stdio. h>
19 # include <string. h>
20 # define n 1200
21 # define maxint 0 xfffffff
22 # define num 40000
23 void Init (), spfa (), print (), addedge (INT, Int, INT );
24 struct edge {
25 int X, Y, W, next;
26} e [5 * num];
27 int head [3 * num], n, k, m = 0, DIS [3 * num], vis [3 * num], ANS = 0, minnum = maxint, maxnum =-maxint, queue [num * 300];
28 int main ()
29 {
30 Init ();
31 spfa ();
32 print ();
33 return 0;
34}
35 void Init ()
36 {
37 int I, j, A, B, C, ch;
38 memset (Head,-1, sizeof (head ));
39 memset (DIS, 0, sizeof (DIS ));
40 scanf ("% d", & K, & N );
41 for (I = 1; I <= N; ++ I ){
42 scanf ("% d", & A, & B );
43 If (A> B ){
44 CH =;
45 A = B;
46 B = CH;
47}
48 A + = num-1;
49 B + = num;
50 minnum = minnum <? Minnum:;
51 maxnum = maxnum> B? Maxnum: B;
52 c = B-;
53 If (C <k ){
54 addedge (A, B, C );
55 addedge (B, A,-C );
56}
57 else
58 addedge (a, B, k );
59}
60}
61 void addedge (int x, int y, int W)
62 {
63 + + m;
64 E [M]. x = X;
65 E [M]. Y = y;
66 E [M]. W = W;
67 E [M]. Next = head [x];
68 head [x] = m;
69}
70
71 void spfa ()
72 {
73 int I, j, X, Y, tail = 0, front = 0;
74 for (I = minnum; I <= maxnum; ++ I ){
75 if (I! = 0 ){
76 queue [++ tail] = I;
77 addedge (I, I + 1, 0 );
78 addedge (I + 1, I,-1 );
79}
80 dis [I] =-maxint;
81 vis [I] = 0;
82}
83 dis [minnum] = 0;
84 vis [minnum] = 1;
85 while (front <tail ){
86 x = queue [++ front];
87 vis [x] = 0;
88 for (I = head [X]; I! =-1; I = E [I]. Next ){
89 y = E [I]. Y;
90 if (DIS [x] + E [I]. W> dis [y]) {
91 dis [y] = E [I]. W + dis [x];
92 If (! Vis [y]) {
93 vis [y] = 1;
94 queue [++ tail] = y;
95}
96}
97}
98}
99}
100
101 void print ()
102 {
103 int I;
104 printf ("% d \ n", DIS [maxnum]);
105 for (I = minnum; I <= maxnum; ++ I)
106 If (DIS [I]-Dis [I-1] = 1)
107 printf ("% d \ n", I-num );
108}