c/c++语言开发共享洛谷P3959 宝藏(模拟退火乱搞)

/*  */  #include<iostream>  #include<cstdio>  #include<cmath>  #include<cstdlib>  #include<ctime>  #include<cstring>  #include<algorithm>  #include<vector>  #define pair pair<int, int>   #define mp(x, y) make_pair(x, y)  #define fi first  #define se second  using namespace std;  const int maxn = 1001;  const double eps = 1e-10, dlt = 0.97, inf = 1e9 + 7;  inline int read() {      char c = getchar(); int x = 0, f = 1;      while(c < '0' || c > '9') {if(c == '-') f = -1; c = getchar();}      while(c >= '0' && c <= '9') x = x * 10 + c - '0', c = getchar();      return x * f;  }  int n, m;  struct edge {      int u, v, w;      bool operator < (const edge &rhs) const {          return w < rhs.w;      }  }e[maxn];  int link[maxn][maxn], num, fa[maxn];  void unionn(int x, int y) {      fa[x] = y;  }  int find(int x) {      if(fa[x] == x) return fa[x];      else return fa[x] = find(fa[x]);  }  vector<pair> v[maxn];  int dfs(int x, int cnt, int fa) {      int ans = 0;      for(int i = 0; i < v[x].size(); i++) {          int to = v[x][i].fi, w = v[x][i].se;          if(to != fa) ans += dfs(to, cnt + 1, x) + w * cnt;      }      return ans;  }  int solve() {      int cur = inf, tot = 0, base = 0;      for(int i = 1; i <= n; i++) fa[i] = i, v[i].clear();      for(int i = 1; i <= m; i++) {          int x = e[i].u, y = e[i].v;          int fx = find(x), fy = find(y);          if(fx == fy) continue;          tot++; unionn(fx, fy);           v[x].push_back(mp(y, e[i].w));          v[y].push_back(mp(x, e[i].w));      }      if(tot != n - 1) return inf;      for(int i = 1; i <= n; i++)          cur = min(cur, dfs(i, 1, 0));      return cur;  }  int main() {  //    freopen("testdata.in", "r", stdin);      srand((unsigned)time(null));      memset(link, 0x7f, sizeof(link));      n = read(); m = read();      if(n == 1) {          puts("0"); return 0;      }      for(int i = 1; i <= m; i++) {          int x = read(), y = read(), w = read();          link[x][y] = min(link[x][y], w);          link[y][x] = min(link[y][x], w);      }      for(int i = 1; i <= n; i++)           for(int j = i + 1; j <= n; j++)               if(link[i][j] <= inf)                   e[++num] = (edge) {i, j, link[i][j]};      sort(e + 1, e + num + 1);      int ans = solve();      int times = 200;      while(times--) {          int now = inf;          for(double t = 100000; t > eps; t *= dlt) {              int x = rand() % num + 1, y = rand() % num + 1;              //check(x, y);              swap(e[x], e[y]);              int nxt = solve();              if(nxt < ans) {ans = nxt; continue;}              if(nxt < now || ((exp(now - nxt / t) < rand() / rand_max))) {now = nxt; continue;}              swap(e[x], e[y]);          }      }      printf("%d", ans);      return 0;  }  /*  4  0 0  0 5000  2354 10000  8787 0  */