ZOJ 3668 Launching the Spacecraft (差分约束系统，最短路)

  1 /********************************************
  2 *ACM Solutions
  3 *
  4 *@Title: ZOJ 3668 Launching the Spacecraft
  5 *@Version: 1.0
  6 *@Time: 2014-08-26
  7 *@Solution: http://www.cnblogs.com/xysmlx/p/xxxxxxx.html
  8 *
  9 *@Author: xysmlx(Lingxiao Ma)
 10 *@Blog: http://www.cnblogs.com/xysmlx
 11 *@EMail: xysmlx@163.com
 12 *
 13 *Copyright (C) 2011-2015 xysmlx(Lingxiao Ma)
 14 ********************************************/
 15 // #pragma comment(linker, "/STACK:102400000,102400000")
 16 #include <cstdio>
 17 #include <iostream>
 18 #include <cstring>
 19 #include <string>
 20 #include <cmath>
 21 #include <set>
 22 #include <list>
 23 #include <map>
 24 #include <iterator>
 25 #include <cstdlib>
 26 #include <vector>
 27 #include <queue>
 28 #include <stack>
 29 #include <algorithm>
 30 #include <functional>
 31 using namespace std;
 32 typedef long long LL;
 33 #define pb push_back
 34 #define ROUND(x) round(x)
 35 #define FLOOR(x) floor(x)
 36 #define CEIL(x) ceil(x)
 37 const int maxn = 1010;
 38 const int maxm = 2000010;
 39 const int inf = 0x3f3f3f3f;
 40 const LL inf64 = 0x3f3f3f3f3f3f3f3fLL;
 41 const double INF = 1e30;
 42 const double eps = 1e-6;
 43 const int P[4] = {0, 0, -1, 1};
 44 const int Q[4] = {1, -1, 0, 0};
 45 const int PP[8] = { -1, -1, -1, 0, 0, 1, 1, 1};
 46 const int QQ[8] = { -1, 0, 1, -1, 1, -1, 0, 1};
 47 struct Edge
 48 {
 49     int u, v, w;
 50     int next;
 51 } edge[maxm];
 52 int head[maxn], en;
 53 void addse(int u, int v, int w)
 54 {
 55     edge[en].u = u;
 56     edge[en].v = v;
 57     edge[en].w = w;
 58     edge[en].next = head[u];
 59     head[u] = en++;
 60 }
 61 
 62 int n, m;
 63 int d[maxn];
 64 int pre[maxn];//用于解析路径
 65 /*DFS找负环
 66 bool cir[maxn];
 67 void dfs(int u)
 68 {
 69     cir[u]=true;
 70     for(int i=head[u]; i!=-1; i=edge[i].next)
 71         if(!cir[edge[i].v]) dfs(edge[i].v);
 72 }
 73 */
 74 bool spfa(int s)
 75 {
 76     int cnt[maxn];
 77     int mark[maxn];
 78     queue<int> Q;
 79     for (int i = 0; i <= n; ++i) d[i] = inf;
 80     for (int i = 0; i <= n; ++i) pre[i] = i; //用于解析路径
 81     memset(mark, 0, sizeof(mark));
 82     memset(cnt, 0, sizeof(cnt));
 83     d[s] = 0;
 84     Q.push(s);
 85     mark[s] = 1;
 86     cnt[s]++;
 87     while (Q.size())
 88     {
 89         int u = Q.front();
 90         Q.pop();
 91         mark[u] = 0;
 92         for (int i = head[u]; i != -1; i = edge[i].next)
 93         {
 94             int v = edge[i].v;
 95             int w = edge[i].w;
 96             if (d[u] + w < d[v])
 97             {
 98                 pre[v] = u; // 用于解析路径
 99                 d[v] = d[u] + w;
100                 if (mark[v] == 0)
101                 {
102                     mark[v] = 1;
103                     Q.push(v);
104                     if (++cnt[v] > n + 1) return false; //有负环，可以用DFS找
105                 }
106             }
107         }
108     }
109     return true;
110 }
111 int kase;
112 void init()
113 {
114     kase++;
115     memset(head, -1, sizeof(head));
116     en = 0;
117 }
118 void add(int l, int r, int a, int b)
119 {
120     addse(l - 1, r, b);
121     addse(r, l - 1, -a);
122 }
123 void input()
124 {
125     for (int i = 1; i <= n; i++)
126     {
127         addse(i, i - 1, 10000);
128         addse(i - 1, i, 10000);
129     }
130     for (int i = 0; i < m; i++)
131     {
132         int l, r, a, b;
133         scanf("%d%d%d%d", &l, &r, &a, &b);
134         add(l, r, a, b);
135     }
136 }
137 void debug()
138 {
139     //
140 }
141 void solve()
142 {
143     if (spfa(0))
144     {
145         for (int i = 1; i <= n; i++)
146         {
147             if (i < n) printf("%d ", d[i] - d[i - 1]);
148             else printf("%d\n", d[i] - d[i - 1]);
149         }
150     }
151     else puts("The spacecraft is broken!");
152 }
153 void output()
154 {
155     //
156 }
157 int main()
158 {
159     // int size = 256 << 20; // 256MB
160     // char *p = (char *)malloc(size) + size;
161     // __asm__("movl %0, %%esp\n" :: "r"(p));
162 
163     // std::ios_base::sync_with_stdio(false);
164 #ifdef xysmlx
165     freopen("in.cpp", "r", stdin);
166 #endif
167 
168     kase = 0;
169     while (~scanf("%d%d", &n, &m))
170     {
171         init();
172         input();
173         solve();
174         output();
175     }
176     return 0;
177 }