【BestCoder】 HDOJ 5174 Ferries Wheel

注意只有一个轮子的时候要输出-1，不是n==1的时候输出-1.。。。

#include <iostream>#include <queue> #include <stack> #include <map> #include <set> #include <bitset> #include <cstdio> #include <algorithm> #include <cstring> #include <climits>#include <cstdlib>#include <cmath>#include <time.h>#define maxn 200005#define maxm 4005#define eps 1e-7#define mod 1000000007#define INF 0x3f3f3f3f#define PI (acos(-1.0))#define lowbit(x) (x&(-x))#define mp make_pair#define ls o<<1#define rs o<<1 | 1#define lson o<<1, L, mid #define rson o<<1 | 1, mid+1, R#define pii pair<int, int>#pragma comment(linker, "/STACK:16777216")typedef long long LL;typedef unsigned long long ULL;//typedef int LL;using namespace std;LL qpow(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base;base=base*base;b/=2;}return res;}LL powmod(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base%mod;base=base*base%mod;b/=2;}return res;}// headstruct node{int u, v;ULL w;}e[maxn];int f[maxn];ULL c[maxn];ULL res1[maxn];ULL res2[maxn];int n;ULL ans1;int cmp1(node a, node b){return a.w < b.w;}int cmp2(node a, node b){return a.w > b.w;}int find(int u){return f[u] = u == f[u] ? f[u] : find(f[u]);}void merge1(int a, int b, ULL w){int aa = find(a), bb = find(b);if(aa != bb) {ULL t1 = c[aa] * c[bb] * w;f[bb] = aa;c[aa] += c[bb];ans1 += t1;}}void merge2(int a, int b, ULL w){int aa = find(a), bb = find(b);if(aa != bb) {ULL t1 = c[aa] * c[bb] * w;f[bb] = aa;c[aa] += c[bb];ans1 -= t1;}}void read(){for(int i = 1; i < n; i++)scanf("%d%d%d", &e[i].u, &e[i].v, &e[i].w);}void work(){for(int i = 0; i <= n; i++) c[i] = 1;for(int i = 0; i <= n; i++) f[i] = i;sort(e+1, e+n, cmp1);ans1 = 0;for(int i = 1; i < n; i++) merge1(e[i].u, e[i].v, e[i].w);for(int i = 0; i <= n; i++) c[i] = 1;for(int i = 0; i <= n; i++) f[i] = i;sort(e+1, e+n, cmp2);for(int i = 1; i < n; i++) merge2(e[i].u, e[i].v, e[i].w);cout << ans1 << endl;}int main(){int _ = 0;while(scanf("%d", &n)!=EOF) {read();printf("Case #%d: ", ++_);work();}return 0;}