UVa 12661 Funny Car Racing - spfa
很简单的一道最短路问题。分情况处理赛道的打开和关闭。
Code
1 /** 2 * UVa 3 * Problem#12661 4 * Accepted 5 * Time:50ms 6 */ 7 #include<iostream> 8 #include<fstream> 9 #include<sstream> 10 #include<cstdio> 11 #include<cstdlib> 12 #include<cstring> 13 #include<ctime> 14 #include<cctype> 15 #include<cmath> 16 #include<algorithm> 17 #include<stack> 18 #include<queue> 19 #include<set> 20 #include<map> 21 #include<vector> 22 using namespace std; 23 typedef bool boolean; 24 #define smin(a, b) (a) = min((a), (b)) 25 #define smax(as, b) (a) = max((a), (b)) 26 template<typename T> 27 inline boolean readInteger(T& u){ 28 char x; 29 int aFlag = 1; 30 while(!isdigit((x = getchar())) && x != '-' && x != -1); 31 if(x == -1) return false; 32 if(x == '-'){ 33 x = getchar(); 34 aFlag = -1; 35 } 36 for(u = x - '0'; isdigit((x = getchar())); u = (u << 3) + (u << 1) + x - '0'); 37 ungetc(x, stdin); 38 u *= aFlag; 39 return true; 40 } 41 42 typedef class Edge{ 43 public: 44 int end; 45 int next; 46 int open; 47 int close; 48 int t; 49 Edge(const int end = 0, const int next = 0, const int open = 0, const int close = 0, const int t = 0):end(end), next(next), open(open), close(close), t(t){ } 50 int across(int arrived){ 51 int re = arrived % (open + close); 52 if(re >= 0 && re + t <= open) return arrived + t; 53 return (arrived / (open + close) + 1) * (open + close) + t; 54 } 55 }Edge; 56 57 typedef class MapManager{ 58 public: 59 int ce; 60 Edge* edges; 61 int* h; 62 MapManager():ce(0), edges(NULL), h(NULL){ } 63 MapManager(int points, int limit):ce(0){ 64 h = new int[(const int)(points + 1)]; 65 edges = new Edge[(const int)(limit + 1)]; 66 memset(h, 0, sizeof(int) * (points + 1)); 67 } 68 inline void addEdge(int from, int end, int open, int close, int t){ 69 if(t > open) return; //无法通过 70 edges[++ce] = Edge(end, h[from], open, close, t); 71 h[from] = ce; 72 } 73 Edge& operator [](int pos){ 74 return edges[pos]; 75 } 76 void clear(){ 77 delete[] edges; 78 delete[] h; 79 ce = 0; 80 } 81 }MapManager; 82 83 #define m_begin(g, i) (g).h[(i)] 84 85 int n, m, from, _end; 86 MapManager g; 87 88 inline boolean init(){ 89 if(!readInteger(n)) return false; 90 readInteger(m); 91 readInteger(from); 92 readInteger(_end); 93 g = MapManager(n, m); 94 for(int i = 1, u, v, a, b, t; i <= m; i++){ 95 readInteger(u); 96 readInteger(v); 97 readInteger(a); 98 readInteger(b); 99 readInteger(t); 100 g.addEdge(u, v, a, b, t); 101 } 102 return true; 103 } 104 105 boolean* visited; 106 queue<int> que; 107 int* f; 108 inline int spfa(int s, int t){ 109 que.push(s); 110 visited[s] = true; 111 f[s] = 0; 112 while(!que.empty()){ 113 int e = que.front(); 114 que.pop(); 115 visited[e] = false; 116 for(int i = m_begin(g, e); i != 0; i = g[i].next){ 117 int& eu = g[i].end; 118 int cmp = g[i].across(f[e]); 119 if(cmp < f[eu]){ 120 f[eu] = cmp; 121 if(!visited[eu] && eu != t){ 122 que.push(eu); 123 visited[eu] = true; 124 } 125 } 126 } 127 } 128 return f[t]; 129 } 130 131 inline void solve(){ 132 visited = new boolean[(const int)(n + 1)]; 133 f = new int[(const int)(n + 1)]; 134 memset(visited, false, sizeof(boolean) * (n + 1)); 135 memset(f, 0x7f, sizeof(int) * (n + 1)); 136 int res = spfa(from, _end); 137 printf("%d\n", res); 138 } 139 140 inline void clear(){ 141 g.clear(); 142 delete[] visited; 143 delete[] f; 144 } 145 146 int main(){ 147 int kase = 1; 148 while(init()){ 149 printf("Case %d: ", kase++); 150 solve(); 151 clear(); 152 } 153 return 0; 154 }
