题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=2874
这题有不连通的情况，特别注意。
觉得是存query的姿势不对，用前向星存了一遍，还是T……
1 /* 2 ━━━━━┒ギリギリ♂ eye！ 3 ┓┏┓┏┓┃キリキリ♂ mind！ 4 ┛┗┛┗┛┃＼○／ 5 ┓┏┓┏┓┃ / 6 ┛┗┛┗┛┃ノ) 7 ┓┏┓┏┓┃ 8 ┛┗┛┗┛┃ 9 ┓┏┓┏┓┃ 10 ┛┗┛┗┛┃ 11 ┓┏┓┏┓┃ 12 ┛┗┛┗┛┃ 13 ┓┏┓┏┓┃ 14 ┃┃┃┃┃┃ 15 ┻┻┻┻┻┻ 16 */ 17 #include <algorithm> 18 #include <iostream> 19 #include <iomanip> 20 #include <cstring> 21 #include <climits> 22 #include <complex> 23 #include <fstream> 24 #include <cassert> 25 #include <cstdio> 26 #include <bitset> 27 #include <vector> 28 #include <deque> 29 #include <queue> 30 #include <stack> 31 #include <ctime> 32 #include <set> 33 #include <map> 34 #include <cmath> 35 using namespace std; 36 #define fr first 37 #define sc second 38 #define cl clear 39 #define BUG puts("here!!!") 40 #define W(a) while(a--) 41 #define pb(a) push_back(a) 42 #define Rint(a) scanf("%d", &a) 43 #define Rll(a) scanf("%lld", &a) 44 #define Rs(a) scanf("%s", a) 45 #define Cin(a) cin >> a 46 #define FRead() freopen("in", "r", stdin) 47 #define FWrite() freopen("out", "w", stdout) 48 #define Rep(i, len) for(int i = 0; i < (len); i++) 49 #define For(i, a, len) for(int i = (a); i < (len); i++) 50 #define Cls(a) memset((a), 0, sizeof(a)) 51 #define Clr(a, x) memset((a), (x), sizeof(a)) 52 #define Full(a) memset((a), 0x7f7f, sizeof(a)) 53 #define lp p << 1 54 #define rp p << 1 | 1 55 #define pi 3.14159265359 56 #define RT return 57 #define lowbit(x) x & (-x) 58 #define onenum(x) __builtin_popcount(x) 59 typedef long long LL; 60 typedef long double LD; 61 typedef unsigned long long ULL; 62 typedef pair<int, int> pii; 63 typedef pair<string, int> psi; 64 typedef map<string, int> msi; 65 typedef vector<int> vi; 66 typedef vector<LL> vl; 67 typedef vector<vl> vvl; 68 typedef vector<bool> vb; 69 70 typedef struct Query { 71 int idx; 72 int u, v; 73 Query() {} 74 Query(int uu, int vv, int ii) : u(uu), v(vv), idx(ii) {} 75 }Query; 76 77 typedef struct Edge { 78 int u, v, w, idx; 79 int next; 80 Edge() {} 81 Edge(int uu, int vv, int ww) : u(uu), v(vv), w(ww) {} 82 }Edge; 83 84 typedef struct Ans { 85 int idx; 86 int ans; 87 Ans() {} 88 Ans(int aa, int ii) :ans(aa), idx(ii) {} 89 }Ans; 90 91 const int maxn = 20010; 92 const int maxm = 2000010; 93 int n, m, c, qcnt; 94 int depth[maxn]; 95 bool vis[maxn]; 96 int pre[maxn]; 97 Ans ans[maxm]; 98 Edge edge[maxn]; 99 Edge q[maxm]; 100 Query qq[maxm]; 101 int qhead[maxm]; 102 int head[maxn]; 103 int ecnt; 104 int u, v, w; 105 106 void adde(int u, int v, int w) { 107 edge[ecnt].u = u; 108 edge[ecnt].v = v; 109 edge[ecnt].w = w; 110 edge[ecnt].next = head[u]; 111 head[u] = ecnt++; 112 } 113 114 void addq(int u, int v, int i) { 115 q[qcnt].u = u; 116 q[qcnt].v = v; 117 q[qcnt].idx = i; 118 q[qcnt].next = qhead[u]; 119 qhead[u] = ecnt++; 120 } 121 122 int find(int x) { 123 return x == pre[x] ? x : pre[x] = find(pre[x]); 124 } 125 126 void unite(int x, int y) { 127 x = find(x); 128 y = find(y); 129 if(x != y) pre[y] = x; 130 } 131 132 void dfs(int u, int p, int d) { 133 depth[u] = d; 134 for(int i = head[u]; ~i; i=edge[i].next) { 135 int v = edge[i].v; 136 if(!vis[v] && v != p) { 137 dfs(v, u, d+edge[i].w); 138 unite(u, v); 139 } 140 } 141 vis[u] = 1; 142 for(int i = qhead[u]; ~i; i=q[i].next) { 143 int uu = q[i].u; 144 int vv = q[i].v; 145 int idx = q[i].idx; 146 if((vis[vv] && uu == u) || (vis[uu] && vv == u)) { 147 ans[idx].ans = depth[vv] + depth[uu]; 148 } 149 } 150 } 151 152 bool cmp(Ans x, Ans y) { 153 return x.idx < y.idx; 154 } 155 156 int ufs[maxn]; 157 158 int find1(int x) { 159 return ufs[x] == x ? x : ufs[x] = find1(ufs[x]); 160 } 161 162 void unite1(int x, int y) { 163 x = find1(x); 164 y = find1(y); 165 if(x != y) ufs[y] = x; 166 } 167 168 inline bool scan_d(int &num) { 169 char in;bool IsN=false; 170 in=getchar(); 171 if(in==EOF) return false; 172 while(in!='-'&&(in<'0'||in>'9')) in=getchar(); 173 if(in=='-'){ IsN=true;num=0;} 174 else num=in-'0'; 175 while(in=getchar(),in>='0'&&in<='9'){ 176 num*=10,num+=in-'0'; 177 } 178 if(IsN) num=-num; 179 return true; 180 } 181 182 int main() { 183 // FRead(); 184 while(~scanf("%d%d%d",&n,&m,&c)) { 185 Cls(vis); Cls(depth); Cls(ans); Clr(head, -1); Clr(qhead, -1); 186 qcnt = 0; Rep(i, n+5) pre[i] = i, ufs[i] = i; 187 Rep(i, m) { 188 scan_d(u); scan_d(v); scan_d(w); 189 adde(u, v, w); adde(v, u, w); 190 unite1(u, v); 191 } 192 Rep(i, c) { 193 scan_d(u); scan_d(v); 194 addq(u, v, i); 195 qq[i] = Query(u, v, i); 196 } 197 For(i, 1, n+1) if(!vis[i]) dfs(i, -1, 0); 198 Rep(i, c) { 199 if(find1(qq[ans[i].idx].u) != find1(qq[ans[i].idx].v)) puts("Not connected"); 200 else printf("%d ", ans[i].ans); 201 } 202 } 203 RT 0; 204 }
……TARJAN也T了……
1 /* 2 ━━━━━┒ギリギリ♂ eye！ 3 ┓┏┓┏┓┃キリキリ♂ mind！ 4 ┛┗┛┗┛┃＼○／ 5 ┓┏┓┏┓┃ / 6 ┛┗┛┗┛┃ノ) 7 ┓┏┓┏┓┃ 8 ┛┗┛┗┛┃ 9 ┓┏┓┏┓┃ 10 ┛┗┛┗┛┃ 11 ┓┏┓┏┓┃ 12 ┛┗┛┗┛┃ 13 ┓┏┓┏┓┃ 14 ┃┃┃┃┃┃ 15 ┻┻┻┻┻┻ 16 */ 17 #include <algorithm> 18 #include <iostream> 19 #include <iomanip> 20 #include <cstring> 21 #include <climits> 22 #include <complex> 23 #include <fstream> 24 #include <cassert> 25 #include <cstdio> 26 #include <bitset> 27 #include <vector> 28 #include <deque> 29 #include <queue> 30 #include <stack> 31 #include <ctime> 32 #include <set> 33 #include <map> 34 #include <cmath> 35 using namespace std; 36 #define fr first 37 #define sc second 38 #define cl clear 39 #define BUG puts("here!!!") 40 #define W(a) while(a--) 41 #define pb(a) push_back(a) 42 #define Rint(a) scanf("%d", &a) 43 #define Rll(a) scanf("%lld", &a) 44 #define Rs(a) scanf("%s", a) 45 #define Cin(a) cin >> a 46 #define FRead() freopen("in", "r", stdin) 47 #define FWrite() freopen("out", "w", stdout) 48 #define Rep(i, len) for(int i = 0; i < (len); i++) 49 #define For(i, a, len) for(int i = (a); i < (len); i++) 50 #define Cls(a) memset((a), 0, sizeof(a)) 51 #define Clr(a, x) memset((a), (x), sizeof(a)) 52 #define Full(a) memset((a), 0x7f7f, sizeof(a)) 53 #define lp p << 1 54 #define rp p << 1 | 1 55 #define pi 3.14159265359 56 #define RT return 57 #define lowbit(x) x & (-x) 58 #define onenum(x) __builtin_popcount(x) 59 typedef long long LL; 60 typedef long double LD; 61 typedef unsigned long long ULL; 62 typedef pair<int, int> pii; 63 typedef pair<string, int> psi; 64 typedef map<string, int> msi; 65 typedef vector<int> vi; 66 typedef vector<LL> vl; 67 typedef vector<vl> vvl; 68 typedef vector<bool> vb; 69 70 typedef struct Query { 71 int idx; 72 int u, v; 73 Query() {} 74 Query(int uu, int vv, int ii) : u(uu), v(vv), idx(ii) {} 75 }Query; 76 77 typedef struct Edge { 78 int u, v, w; 79 int next; 80 Edge() {} 81 Edge(int uu, int vv, int ww) : u(uu), v(vv), w(ww) {} 82 }Edge; 83 84 typedef struct Ans { 85 int idx; 86 int ans; 87 Ans() {} 88 Ans(int aa, int ii) :ans(aa), idx(ii) {} 89 }Ans; 90 91 const int maxn = 20010; 92 const int maxm = 2000010; 93 int n, m, c, qcnt; 94 int depth[maxn]; 95 bool vis[maxn]; 96 int pre[maxn]; 97 Query q[maxm]; 98 Ans ans[maxm]; 99 Edge edge[maxn]; 100 int head[maxn]; 101 int ecnt; 102 int u, v, w; 103 104 void adde(int u, int v, int w) { 105 edge[ecnt].u = u; 106 edge[ecnt].v = v; 107 edge[ecnt].w = w; 108 edge[ecnt].next = head[u]; 109 head[u] = ecnt++; 110 } 111 112 int find(int x) { 113 return x == pre[x] ? x : pre[x] = find(pre[x]); 114 } 115 116 void unite(int x, int y) { 117 x = find(x); 118 y = find(y); 119 if(x != y) pre[y] = x; 120 } 121 122 void dfs(int u, int p, int d) { 123 depth[u] = d; 124 for(int i = head[u]; ~i; i=edge[i].next) { 125 int v = edge[i].v; 126 if(!vis[v] && v != p) { 127 dfs(v, u, d+edge[i].w); 128 unite(u, v); 129 } 130 } 131 vis[u] = 1; 132 Rep(i, qcnt) { 133 int uu = q[i].u; 134 int vv = q[i].v; 135 int idx = q[i].idx; 136 if((vis[vv] && uu == u) || (vis[uu] && vv == u)) { 137 ans[idx].idx = idx; 138 ans[idx].ans = depth[vv] + depth[uu]; 139 } 140 } 141 } 142 143 bool cmp(Ans x, Ans y) { 144 return x.idx < y.idx; 145 } 146 147 int ufs[maxn]; 148 149 int find1(int x) { 150 return ufs[x] == x ? x : ufs[x] = find1(ufs[x]); 151 } 152 153 void unite1(int x, int y) { 154 x = find1(x); 155 y = find1(y); 156 if(x != y) ufs[y] = x; 157 } 158 159 inline bool scan_d(int &num) { 160 char in;bool IsN=false; 161 in=getchar(); 162 if(in==EOF) return false; 163 while(in!='-'&&(in<'0'||in>'9')) in=getchar(); 164 if(in=='-'){ IsN=true;num=0;} 165 else num=in-'0'; 166 while(in=getchar(),in>='0'&&in<='9'){ 167 num*=10,num+=in-'0'; 168 } 169 if(IsN) num=-num; 170 return true; 171 } 172 173 int main() { 174 // FRead(); 175 while(~scanf("%d%d%d",&n,&m,&c)) { 176 Cls(vis); Cls(depth); Cls(ans); Clr(head, -1); 177 qcnt = 0; Rep(i, n+5) pre[i] = i, ufs[i] = i; 178 Rep(i, m) { 179 scan_d(u); scan_d(v); scan_d(w); 180 adde(u, v, w); adde(v, u, w); 181 unite1(u, v); 182 } 183 Rep(i, c) { 184 scan_d(u); scan_d(v); 185 q[qcnt++] = Query(u, v, i); 186 } 187 For(i, 1, n+1) if(!vis[i]) dfs(i, -1, 0); 188 Rep(i, c) { 189 if(find1(q[ans[i].idx].u) != find1(q[ans[i].idx].v)) puts("Not connected"); 190 else printf("%d ", ans[i].ans); 191 } 192 } 193 RT 0; 194 }
在线胡搞T了，等下写个离线的。
TLE代码：
1 /* 2 ━━━━━┒ギリギリ♂ eye！ 3 ┓┏┓┏┓┃キリキリ♂ mind！ 4 ┛┗┛┗┛┃＼○／ 5 ┓┏┓┏┓┃ / 6 ┛┗┛┗┛┃ノ) 7 ┓┏┓┏┓┃ 8 ┛┗┛┗┛┃ 9 ┓┏┓┏┓┃ 10 ┛┗┛┗┛┃ 11 ┓┏┓┏┓┃ 12 ┛┗┛┗┛┃ 13 ┓┏┓┏┓┃ 14 ┃┃┃┃┃┃ 15 ┻┻┻┻┻┻ 16 */ 17 #include <algorithm> 18 #include <iostream> 19 #include <iomanip> 20 #include <cstring> 21 #include <climits> 22 #include <complex> 23 #include <fstream> 24 #include <cassert> 25 #include <cstdio> 26 #include <bitset> 27 #include <vector> 28 #include <deque> 29 #include <queue> 30 #include <stack> 31 #include <ctime> 32 #include <set> 33 #include <map> 34 #include <cmath> 35 using namespace std; 36 #define fr first 37 #define sc second 38 #define cl clear 39 #define BUG puts("here!!!") 40 #define W(a) while(a--) 41 #define pb(a) push_back(a) 42 #define Rint(a) scanf("%d", &a) 43 #define Rll(a) scanf("%I64d", &a) 44 #define Rs(a) scanf("%s", a) 45 #define Cin(a) cin >> a 46 #define FRead() freopen("in", "r", stdin) 47 #define FWrite() freopen("out", "w", stdout) 48 #define Rep(i, len) for(int i = 0; i < (len); i++) 49 #define For(i, a, len) for(int i = (a); i < (len); i++) 50 #define Cls(a) memset((a), 0, sizeof(a)) 51 #define Clr(a, x) memset((a), (x), sizeof(a)) 52 #define Full(a) memset((a), 0x7f7f, sizeof(a)) 53 #define pi 3.14159265359 54 #define RT return 55 #define lowbit(x) x & (-x) 56 #define onenum(x) __builtin_popcount(x) 57 typedef long long LL; 58 typedef long double LD; 59 typedef unsigned long long ULL; 60 typedef pair<int, int> pii; 61 typedef pair<string, int> psi; 62 typedef map<string, int> msi; 63 typedef vector<int> vi; 64 typedef vector<LL> vl; 65 typedef vector<vl> vvl; 66 typedef vector<bool> vb; 67 68 typedef struct Edge { 69 int u, v, w; 70 int next; 71 }Edge; 72 const int maxn = 10010; 73 const int maxm = 10010; 74 int n, m, c; 75 int depth[maxn], fa[maxn]; 76 int pre[maxn]; 77 Edge edge[maxm]; 78 int head[maxn]; 79 int ecnt; 80 bool vis[maxn]; 81 82 void adde(int u, int v, int w) { 83 edge[ecnt].u = u; 84 edge[ecnt].v = v; 85 edge[ecnt].w = w; 86 edge[ecnt].next = head[u]; 87 head[u] = ecnt++; 88 } 89 90 int find(int x) { 91 x == pre[x] ? x : pre[x] = find(pre[x]); 92 } 93 94 void unite(int x, int y) { 95 x = find(x); 96 y = find(y); 97 if(x != y) pre[y] = x; 98 } 99 100 void dfs(int u, int p, int d) { 101 vis[u] = 1; 102 depth[u] = d; fa[u] = p; 103 for(int i = head[u]; ~i; i=edge[i].next) { 104 int v = edge[i].v; 105 int w = edge[i].w; 106 if(!vis[v]) dfs(v, u, d+w); 107 } 108 } 109 110 int lca(int u, int v) { 111 int s = 0; 112 while(depth[u] > depth[v]) { 113 s += depth[u]; 114 u = pre[u]; 115 } 116 while(depth[v] > depth[u]) { 117 s += depth[v]; 118 v = pre[v]; 119 } 120 while(u != v) { 121 s += (depth[u] + depth[v]); 122 u = pre[u]; 123 v = pre[v]; 124 } 125 return s; 126 } 127 128 inline bool scan_d(int &num) { 129 char in;bool IsN=false; 130 in=getchar(); 131 if(in==EOF) return false; 132 while(in!='-'&&(in<'0'||in>'9')) in=getchar(); 133 if(in=='-'){ IsN=true;num=0;} 134 else num=in-'0'; 135 while(in=getchar(),in>='0'&&in<='9'){ 136 num*=10,num+=in-'0'; 137 } 138 if(IsN) num=-num; 139 return true; 140 } 141 142 int main() { 143 FRead(); 144 int u, v, w; 145 while(~scanf("%d%d%d",&n,&m,&c)) { 146 Clr(head, -1); ecnt = 0; 147 Rep(i, n+5) pre[i] = i; 148 Rep(i, m) { 149 scan_d(u); scan_d(v); scan_d(w); 150 adde(u, v, w); adde(v, u, w); 151 unite(u, v); 152 } 153 For(i, 1, n+1) { 154 if(!vis[i]) { 155 dfs(i, -1, 0); 156 } 157 } 158 W(c) { 159 scan_d(u); scan_d(v); 160 if(find(u) != find(v)) puts("Not connected"); 161 else printf("%d ", lca(u, v)); 162 } 163 } 164 RT 0; 165 }