Problem p01671 (C++)

Buggy submission (status: Time Limit Exceeded):
#include <algorithm>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <iomanip>
#include <iostream>
#include <string>
#pragma comment(linker, "/STACK:1024000000,1024000000")
#include <list>
#include <map>
#include <queue>
#include <set>
#include <vector>

using namespace std;
typedef long long LL;
typedef unsigned long long ULL;

#define rep(i, k, n) for (int i = (k); i <= (n); i++)
#define red(i, k, n) for (int i = (k); i >= (n); i--)
#define sqr(x) ((x) * (x))
#define clr(x, y) memset((x), (y), sizeof(x))
#define mod 1000000007
#define MAX(a, b) ((a) > (b) ? (a) : (b))
#define MIN(a, b) ((a) > (b) ? (b) : (a))
// const int maxn = ;

struct Edge {
  int u, v, w, id;
} e[200010];

bool cmp(const Edge &a, const Edge &b) { return a.w < b.w; }

struct tE {
  int v, ord, next;
} te[200010];

int head[100010];
int tet;
LL mst;
LL ans[200010];
int f[100010];
int n, m, cnt;
bool me[200010];
int dep[100010];
int fa[100010];
bool vis[100010];
int fae[100010];

vector<int> ne;

void add(int u, int v, int ord) {
  te[++tet].v = v;
  te[tet].ord = ord;
  te[tet].next = head[u];
  head[u] = tet;
}

int getf(int x) { return x == f[x] ? x : f[x] = getf(f[x]); }

void dfs(int u) {
  vis[u] = 1;
  for (int i = head[u]; ~i; i = te[i].next) {
    int v = te[i].v;
    if (vis[v])
      continue;
    fa[v] = u;
    fae[v] = i;
    dep[v] = dep[u] + 1;
    dfs(v);
  }
}

int main() {
// #define LOCAL
#ifdef LOCAL
  freopen("e:\\read.txt", "r", stdin);
  // freopen("e:\\write.txt","w",stdout);
#endif
  while (cin >> n >> m) {
    ne.clear();
    rep(i, 1, m) {
      scanf("%d%d%d", &e[i].u, &e[i].v, &e[i].w);
      e[i].id = i;
    }
    sort(e + 1, e + 1 + m, cmp);
    rep(i, 1, n) f[i] = i;
    mst = cnt = 0;
    int a, b;
    clr(me, 0);
    clr(head, -1);
    tet = 0;
    rep(i, 1, m) {
      a = e[i].u;
      b = e[i].v;
      if (getf(a) != getf(b)) {
        cnt++;
        mst += e[i].w;
        me[e[i].id] = 1;
        f[getf(a)] = getf(b);
        add(a, b, i);
        add(b, a, i);
      } else {
        ne.push_back(i);
      }
    }
    if (cnt < n - 1) {
      rep(i, 1, m) puts("-1");
      continue;
    }
    rep(i, 1, m) if (!me[i]) ans[i] = mst;
    else ans[i] = -1;
    rep(i, 1, n) f[i] = i;
    clr(dep, 0);
    clr(fa, 0);
    clr(vis, 0);
    dfs(1);
    for (int i = 0; i < ne.size(); i++) {
      a = e[ne[i]].u;
      b = e[ne[i]].v;
      while (getf(a) != getf(b)) {
        if (dep[a] > dep[b])
          swap(a, b);
        int k = te[fae[b]].ord;
        if (ans[e[k].id] == -1)
          ans[e[k].id] = mst - e[k].w + e[ne[i]].w;
        else
          ans[e[k].id] = MIN(ans[e[k].id], mst - e[k].w + e[ne[i]].w);
        f[getf(b)] = getf(fa[b]);
        b = fa[b];
      }
    }
    rep(i, 1, m) { printf("%lld\n", ans[i]); }
  }

  return 0;
}

Fixed submission:
#include <algorithm>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <iomanip>
#include <iostream>
#include <string>
#pragma comment(linker, "/STACK:1024000000,1024000000")
#include <list>
#include <map>
#include <queue>
#include <set>
#include <vector>

using namespace std;
typedef long long LL;
typedef unsigned long long ULL;

#define rep(i, k, n) for (int i = (k); i <= (n); i++)
#define red(i, k, n) for (int i = (k); i >= (n); i--)
#define sqr(x) ((x) * (x))
#define clr(x, y) memset((x), (y), sizeof(x))
#define mod 1000000007
#define MAX(a, b) ((a) > (b) ? (a) : (b))
#define MIN(a, b) ((a) > (b) ? (b) : (a))
// const int maxn = ;

struct Edge {
  int u, v, w, id;
} e[200010];

bool cmp(const Edge &a, const Edge &b) { return a.w < b.w; }

struct tE {
  int v, ord, next;
} te[200010];

int head[100010];
int tet;
LL mst;
LL ans[200010];
int f[100010];
int n, m, cnt;
bool me[200010];
int dep[100010];
int fa[100010];
bool vis[100010];
int fae[100010];

vector<int> ne;

void add(int u, int v, int ord) {
  te[++tet].v = v;
  te[tet].ord = ord;
  te[tet].next = head[u];
  head[u] = tet;
}

int getf(int x) { return x == f[x] ? x : f[x] = getf(f[x]); }

void dfs(int u) {
  vis[u] = 1;
  for (int i = head[u]; ~i; i = te[i].next) {
    int v = te[i].v;
    if (vis[v])
      continue;
    fa[v] = u;
    fae[v] = i;
    dep[v] = dep[u] + 1;
    dfs(v);
  }
}

int main() {
// #define LOCAL
#ifdef LOCAL
  freopen("e:\\read.txt", "r", stdin);
  // freopen("e:\\write.txt","w",stdout);
#endif
  while (cin >> n >> m) {
    ne.clear();
    rep(i, 1, m) {
      scanf("%d%d%d", &e[i].u, &e[i].v, &e[i].w);
      e[i].id = i;
    }
    sort(e + 1, e + 1 + m, cmp);
    rep(i, 1, n) f[i] = i;
    mst = cnt = 0;
    int a, b;
    clr(me, 0);
    clr(head, -1);
    tet = 0;
    rep(i, 1, m) {
      a = e[i].u;
      b = e[i].v;
      if (getf(a) != getf(b)) {
        cnt++;
        mst += e[i].w;
        me[e[i].id] = 1;
        f[getf(a)] = getf(b);
        add(a, b, i);
        add(b, a, i);
      } else {
        ne.push_back(i);
      }
    }
    if (cnt < n - 1) {
      rep(i, 1, m) puts("-1");
      continue;
    }
    rep(i, 1, m) if (!me[i]) ans[i] = mst;
    else ans[i] = -1;
    rep(i, 1, n) f[i] = i;
    clr(dep, 0);
    clr(fa, 0);
    clr(vis, 0);
    dfs(1);
    for (int i = 0; i < ne.size(); i++) {
      a = e[ne[i]].u;
      b = e[ne[i]].v;
      while (getf(a) != getf(b)) {
        if (dep[a] > dep[b])
          swap(a, b);
        int k = te[fae[b]].ord;
        if (ans[e[k].id] == -1)
          ans[e[k].id] = mst - e[k].w + e[ne[i]].w;
        else
          ans[e[k].id] = MIN(ans[e[k].id], mst - e[k].w + e[ne[i]].w);
        f[getf(b)] = getf(fa[b]);
        b = getf(fa[b]);
      }
    }
    rep(i, 1, m) { printf("%lld\n", ans[i]); }
  }

  return 0;
}