[HDOJ2874]Connections between cities（LCA, 离线tarjan）

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……

 /*
 ━━━━━┒ギリギリ♂ eye！
 ┓┏┓┏┓┃キリキリ♂ mind！
 ┛┗┛┗┛┃＼○／
 ┓┏┓┏┓┃ /
 ┛┗┛┗┛┃ノ)
 ┓┏┓┏┓┃
 ┛┗┛┗┛┃
 ┓┏┓┏┓┃
 ┛┗┛┗┛┃
 ┓┏┓┏┓┃
 ┛┗┛┗┛┃
 ┓┏┓┏┓┃
 ┃┃┃┃┃┃
 ┻┻┻┻┻┻
 */
 #include <algorithm>
 #include <iostream>
 #include <iomanip>
 #include <cstring>
 #include <climits>
 #include <complex>
 #include <fstream>
 #include <cassert>
 #include <cstdio>
 #include <bitset>
 #include <vector>
 #include <deque>
 #include <queue>
 #include <stack>
 #include <ctime>
 #include <set>
 #include <map>
 #include <cmath>
 using namespace std;
 #define fr first
 #define sc second
 #define cl clear
 #define BUG puts("here!!!")
 #define W(a) while(a--)
 #define pb(a) push_back(a)
 #define Rint(a) scanf("%d", &a)
 #define Rll(a) scanf("%lld", &a)
 #define Rs(a) scanf("%s", a)
 #define Cin(a) cin >> a
 #define FRead() freopen("in", "r", stdin)
 #define FWrite() freopen("out", "w", stdout)
 #define Rep(i, len) for(int i = 0; i < (len); i++)
 #define For(i, a, len) for(int i = (a); i < (len); i++)
 #define Cls(a) memset((a), 0, sizeof(a))
 #define Clr(a, x) memset((a), (x), sizeof(a))
 #define Full(a) memset((a), 0x7f7f, sizeof(a))
 #define lp p << 1
 #define rp p << 1 | 1
 #define pi 3.14159265359
 #define RT return
 #define lowbit(x) x & (-x)
 #define onenum(x) __builtin_popcount(x)
 typedef long long LL;
 typedef long double LD;
 typedef unsigned long long ULL;
 typedef pair<int, int> pii;
 typedef pair<string, int> psi;
 typedef map<string, int> msi;
 typedef vector<int> vi;
 typedef vector<LL> vl;
 typedef vector<vl> vvl;
 typedef vector<bool> vb;

 typedef struct Query {
     int idx;
     int u, v;
     Query() {}
     Query(int uu, int vv, int ii) : u(uu), v(vv), idx(ii) {}
 }Query;

 typedef struct Edge {
     int u, v, w, idx;
     int next;
     Edge() {}
     Edge(int uu, int vv, int ww) : u(uu), v(vv), w(ww) {}
 }Edge;

 typedef struct Ans {
     int idx;
     int ans;
     Ans() {}
     Ans(int aa, int ii) :ans(aa), idx(ii) {}
 }Ans;

 const int maxn = ;
 const int maxm = ;
 int n, m, c, qcnt;
 int depth[maxn];
 bool vis[maxn];
 int pre[maxn];
 Ans ans[maxm];
 Edge edge[maxn];
 Edge q[maxm];
 Query qq[maxm];
 int qhead[maxm];
 int head[maxn];
 int ecnt;
 int u, v, w;

 void adde(int u, int v, int w) {
     edge[ecnt].u = u;
     edge[ecnt].v = v;
     edge[ecnt].w = w;
     edge[ecnt].next = head[u];
     head[u] = ecnt++;
 }

 void addq(int u, int v, int i) {
     q[qcnt].u = u;
     q[qcnt].v = v;
     q[qcnt].idx = i;
     q[qcnt].next = qhead[u];
     qhead[u] = ecnt++;
 }

 int find(int x) {
     return x == pre[x] ? x : pre[x] = find(pre[x]);
 }

 void unite(int x, int y) {
     x = find(x);
     y = find(y);
     if(x != y) pre[y] = x;
 }

 void dfs(int u, int p, int d) {
     depth[u] = d;
     for(int i = head[u]; ~i; i=edge[i].next) {
         int v = edge[i].v;
         if(!vis[v] && v != p) {
             dfs(v, u, d+edge[i].w);
             unite(u, v);
         }
     }
     vis[u] = ;
     for(int i = qhead[u]; ~i; i=q[i].next) {
         int uu = q[i].u;
         int vv = q[i].v;
         int idx = q[i].idx;
         if((vis[vv] && uu == u) || (vis[uu] && vv == u)) {
             ans[idx].ans = depth[vv] + depth[uu];
         }
     }
 }

 bool cmp(Ans x, Ans y) {
     return x.idx < y.idx;
 }

 int ufs[maxn];

 int find1(int x) {
     return ufs[x] == x ? x : ufs[x] = find1(ufs[x]);
 }

 void unite1(int x, int y) {
     x = find1(x);
     y = find1(y);
     if(x != y) ufs[y] = x;
 }

 inline bool scan_d(int &num) {
     char in;bool IsN=false;
     in=getchar();
     if(in==EOF) return false;
     while(in!='-'&&(in<''||in>'')) in=getchar();
     if(in=='-'){ IsN=true;num=;}
     else num=in-'';
     while(in=getchar(),in>=''&&in<=''){
             num*=,num+=in-'';
     }
     if(IsN) num=-num;
     return true;
 }

 int main() {
     // FRead();
     while(~scanf("%d%d%d",&n,&m,&c)) {
         Cls(vis); Cls(depth); Cls(ans); Clr(head, -); Clr(qhead, -);
         qcnt = ; Rep(i, n+) pre[i] = i, ufs[i] = i;
         Rep(i, m) {
             scan_d(u); scan_d(v); scan_d(w);
             adde(u, v, w); adde(v, u, w);
             unite1(u, v);
         }
         Rep(i, c) {
             scan_d(u); scan_d(v);
             addq(u, v, i);
             qq[i] = Query(u, v, i);
         }
         For(i, , n+) if(!vis[i]) dfs(i, -, );
         Rep(i, c) {
             if(find1(qq[ans[i].idx].u) != find1(qq[ans[i].idx].v)) puts("Not connected");
             else printf("%d\n", ans[i].ans);
         }
     }
     RT ;
 }

……TARJAN也T了……

 /*
 ━━━━━┒ギリギリ♂ eye！
 ┓┏┓┏┓┃キリキリ♂ mind！
 ┛┗┛┗┛┃＼○／
 ┓┏┓┏┓┃ /
 ┛┗┛┗┛┃ノ)
 ┓┏┓┏┓┃
 ┛┗┛┗┛┃
 ┓┏┓┏┓┃
 ┛┗┛┗┛┃
 ┓┏┓┏┓┃
 ┛┗┛┗┛┃
 ┓┏┓┏┓┃
 ┃┃┃┃┃┃
 ┻┻┻┻┻┻
 */
 #include <algorithm>
 #include <iostream>
 #include <iomanip>
 #include <cstring>
 #include <climits>
 #include <complex>
 #include <fstream>
 #include <cassert>
 #include <cstdio>
 #include <bitset>
 #include <vector>
 #include <deque>
 #include <queue>
 #include <stack>
 #include <ctime>
 #include <set>
 #include <map>
 #include <cmath>
 using namespace std;
 #define fr first
 #define sc second
 #define cl clear
 #define BUG puts("here!!!")
 #define W(a) while(a--)
 #define pb(a) push_back(a)
 #define Rint(a) scanf("%d", &a)
 #define Rll(a) scanf("%lld", &a)
 #define Rs(a) scanf("%s", a)
 #define Cin(a) cin >> a
 #define FRead() freopen("in", "r", stdin)
 #define FWrite() freopen("out", "w", stdout)
 #define Rep(i, len) for(int i = 0; i < (len); i++)
 #define For(i, a, len) for(int i = (a); i < (len); i++)
 #define Cls(a) memset((a), 0, sizeof(a))
 #define Clr(a, x) memset((a), (x), sizeof(a))
 #define Full(a) memset((a), 0x7f7f, sizeof(a))
 #define lp p << 1
 #define rp p << 1 | 1
 #define pi 3.14159265359
 #define RT return
 #define lowbit(x) x & (-x)
 #define onenum(x) __builtin_popcount(x)
 typedef long long LL;
 typedef long double LD;
 typedef unsigned long long ULL;
 typedef pair<int, int> pii;
 typedef pair<string, int> psi;
 typedef map<string, int> msi;
 typedef vector<int> vi;
 typedef vector<LL> vl;
 typedef vector<vl> vvl;
 typedef vector<bool> vb;

 typedef struct Query {
     int idx;
     int u, v;
     Query() {}
     Query(int uu, int vv, int ii) : u(uu), v(vv), idx(ii) {}
 }Query;

 typedef struct Edge {
     int u, v, w;
     int next;
     Edge() {}
     Edge(int uu, int vv, int ww) : u(uu), v(vv), w(ww) {}
 }Edge;

 typedef struct Ans {
     int idx;
     int ans;
     Ans() {}
     Ans(int aa, int ii) :ans(aa), idx(ii) {}
 }Ans;

 const int maxn = ;
 const int maxm = ;
 int n, m, c, qcnt;
 int depth[maxn];
 bool vis[maxn];
 int pre[maxn];
 Query q[maxm];
 Ans ans[maxm];
 Edge edge[maxn];
 int head[maxn];
 int ecnt;
 int u, v, w;

 void adde(int u, int v, int w) {
     edge[ecnt].u = u;
     edge[ecnt].v = v;
     edge[ecnt].w = w;
     edge[ecnt].next = head[u];
     head[u] = ecnt++;
 }

 int find(int x) {
     return x == pre[x] ? x : pre[x] = find(pre[x]);
 }

 void unite(int x, int y) {
     x = find(x);
     y = find(y);
     if(x != y) pre[y] = x;
 }

 void dfs(int u, int p, int d) {
     depth[u] = d;
     for(int i = head[u]; ~i; i=edge[i].next) {
         int v = edge[i].v;
         if(!vis[v] && v != p) {
             dfs(v, u, d+edge[i].w);
             unite(u, v);
         }
     }
     vis[u] = ;
     Rep(i, qcnt) {
         int uu = q[i].u;
         int vv = q[i].v;
         int idx = q[i].idx;
         if((vis[vv] && uu == u) || (vis[uu] && vv == u)) {
             ans[idx].idx = idx;
             ans[idx].ans = depth[vv] + depth[uu];
         }
     }
 }

 bool cmp(Ans x, Ans y) {
     return x.idx < y.idx;
 }

 int ufs[maxn];

 int find1(int x) {
     return ufs[x] == x ? x : ufs[x] = find1(ufs[x]);
 }

 void unite1(int x, int y) {
     x = find1(x);
     y = find1(y);
     if(x != y) ufs[y] = x;
 }

 inline bool scan_d(int &num) {
     char in;bool IsN=false;
     in=getchar();
     if(in==EOF) return false;
     while(in!='-'&&(in<''||in>'')) in=getchar();
     if(in=='-'){ IsN=true;num=;}
     else num=in-'';
     while(in=getchar(),in>=''&&in<=''){
             num*=,num+=in-'';
     }
     if(IsN) num=-num;
     return true;
 }

 int main() {
     // FRead();
     while(~scanf("%d%d%d",&n,&m,&c)) {
         Cls(vis); Cls(depth); Cls(ans); Clr(head, -);
         qcnt = ; Rep(i, n+) pre[i] = i, ufs[i] = i;
         Rep(i, m) {
             scan_d(u); scan_d(v); scan_d(w);
             adde(u, v, w); adde(v, u, w);
             unite1(u, v);
         }
         Rep(i, c) {
             scan_d(u); scan_d(v);
             q[qcnt++] = Query(u, v, i);
         }
         For(i, , n+) if(!vis[i]) dfs(i, -, );
         Rep(i, c) {
             if(find1(q[ans[i].idx].u) != find1(q[ans[i].idx].v)) puts("Not connected");
             else printf("%d\n", ans[i].ans);
         }
     }
     RT ;
 }

在线胡搞T了，等下写个离线的。

TLE代码：

 /*
 ━━━━━┒ギリギリ♂ eye！
 ┓┏┓┏┓┃キリキリ♂ mind！
 ┛┗┛┗┛┃＼○／
 ┓┏┓┏┓┃ /
 ┛┗┛┗┛┃ノ)
 ┓┏┓┏┓┃
 ┛┗┛┗┛┃
 ┓┏┓┏┓┃
 ┛┗┛┗┛┃
 ┓┏┓┏┓┃
 ┛┗┛┗┛┃
 ┓┏┓┏┓┃
 ┃┃┃┃┃┃
 ┻┻┻┻┻┻
 */
 #include <algorithm>
 #include <iostream>
 #include <iomanip>
 #include <cstring>
 #include <climits>
 #include <complex>
 #include <fstream>
 #include <cassert>
 #include <cstdio>
 #include <bitset>
 #include <vector>
 #include <deque>
 #include <queue>
 #include <stack>
 #include <ctime>
 #include <set>
 #include <map>
 #include <cmath>
 using namespace std;
 #define fr first
 #define sc second
 #define cl clear
 #define BUG puts("here!!!")
 #define W(a) while(a--)
 #define pb(a) push_back(a)
 #define Rint(a) scanf("%d", &a)
 #define Rll(a) scanf("%I64d", &a)
 #define Rs(a) scanf("%s", a)
 #define Cin(a) cin >> a
 #define FRead() freopen("in", "r", stdin)
 #define FWrite() freopen("out", "w", stdout)
 #define Rep(i, len) for(int i = 0; i < (len); i++)
 #define For(i, a, len) for(int i = (a); i < (len); i++)
 #define Cls(a) memset((a), 0, sizeof(a))
 #define Clr(a, x) memset((a), (x), sizeof(a))
 #define Full(a) memset((a), 0x7f7f, sizeof(a))
 #define pi 3.14159265359
 #define RT return
 #define lowbit(x) x & (-x)
 #define onenum(x) __builtin_popcount(x)
 typedef long long LL;
 typedef long double LD;
 typedef unsigned long long ULL;
 typedef pair<int, int> pii;
 typedef pair<string, int> psi;
 typedef map<string, int> msi;
 typedef vector<int> vi;
 typedef vector<LL> vl;
 typedef vector<vl> vvl;
 typedef vector<bool> vb;

 typedef struct Edge {
     int u, v, w;
     int next;
 }Edge;
 const int maxn = ;
 const int maxm = ;
 int n, m, c;
 int depth[maxn], fa[maxn];
 int pre[maxn];
 Edge edge[maxm];
 int head[maxn];
 int ecnt;
 bool vis[maxn];

 void adde(int u, int v, int w) {
     edge[ecnt].u = u;
     edge[ecnt].v = v;
     edge[ecnt].w = w;
     edge[ecnt].next = head[u];
     head[u] = ecnt++;
 }

 int find(int x) {
     x == pre[x] ? x : pre[x] = find(pre[x]);
 }

 void unite(int x, int y) {
     x = find(x);
     y = find(y);
     if(x != y) pre[y] = x;
 }

 void dfs(int u, int p, int d) {
     vis[u] = ;
     depth[u] = d; fa[u] = p;
     for(int i = head[u]; ~i; i=edge[i].next) {
         int v = edge[i].v;
         int w = edge[i].w;
         if(!vis[v]) dfs(v, u, d+w);
     }
 }

 int lca(int u, int v) {
     int s = ;
     while(depth[u] > depth[v]) {
         s += depth[u];
         u = pre[u];
     }
     while(depth[v] > depth[u]) {
         s += depth[v];
         v = pre[v];
     }
     while(u != v) {
         s += (depth[u] + depth[v]);
         u = pre[u];
         v = pre[v];
     }
     return s;
 }

 inline bool scan_d(int &num) {
     char in;bool IsN=false;
     in=getchar();
     if(in==EOF) return false;
     while(in!='-'&&(in<''||in>'')) in=getchar();
     if(in=='-'){ IsN=true;num=;}
     else num=in-'';
     while(in=getchar(),in>=''&&in<=''){
             num*=,num+=in-'';
     }
     if(IsN) num=-num;
     return true;
 }

 int main() {
     FRead();
     int u, v, w;
     while(~scanf("%d%d%d",&n,&m,&c)) {
         Clr(head, -); ecnt = ;
         Rep(i, n+) pre[i] = i;
         Rep(i, m) {
             scan_d(u); scan_d(v); scan_d(w);
             adde(u, v, w); adde(v, u, w);
             unite(u, v);
         }
         For(i, , n+) {
             if(!vis[i]) {
                 dfs(i, -, );
             }
         }
         W(c) {
             scan_d(u); scan_d(v);
             if(find(u) != find(v)) puts("Not connected");
             else printf("%d\n", lca(u, v));
         }
     }
     RT ;
 }