Submission #91382

#	Time	Username	Problem	Language	Result	Execution time	Memory
91382		mirbek01	Marriage questions (IZhO14_marriage)	C++11	66 / 100	1580 ms	13244 KiB

marriage

# include <bits/stdc++.h>

using namespace std;

const int N = 1e5 + 2;

int n, m, k, mt[N], used[N], ans, L, R;
vector <int> g[N], vr, mr;

bool dfs(int v){
      if(used[v])
            return 0;
      vr.push_back(v);
      used[v] = 1;
      for(int to : g[v]){
            if((to > R || to < L) && to <= n)
                  continue;
            if(mt[to] == -1 || dfs(mt[to])){
                  if(mt[to] == -1)
                        mr.push_back(to);
                  if(mt[v] == -1)
                        mr.push_back(v);
                  mt[to] = v;
                  mt[v] = to;
                  return true;
            }
      }
      return false;
}

bool check(){
      if(mt[L] == -1)
            return true;
      for(int i = n + 1; i <= n + m; i ++){
            if(mt[i] == -1){
                  if(!dfs(i)){
                        for(int j = 0; j < (int)vr.size(); j ++)
                              used[vr[j]] = 0;
                        return false;
                  }
                  for(int j = 0; j < (int)vr.size(); j ++)
                        used[vr[j]] = 0;
            }
      }
      return true;
}

bool ok(){
      for(int i = 0; i < (int)mr.size(); i ++)
            mt[ mr[i] ] = -1;
      mr.clear();
      for(int i = n + 1; i <= n + m; i ++){
            for(int j = 0; j < (int)vr.size(); j ++){
                  used[ vr[j] ] = 0;
            }
            vr.clear();
            dfs(i);
      }
      for(int i = n + 1; i <= n + m; i ++){
            if(mt[i] == -1)
                  return false;
      }
      return true;
}

int main(){
      scanf("%d %d %d", &n, &m, &k);

      for(int i = 1; i <= k; i ++){
            int a, b;
            scanf("%d %d", &a, &b);
            g[a].push_back(b + n);
            g[b + n].push_back(a);
      }

      for(int i = 1; i <= n + m; i ++){
            sort(g[i].begin(), g[i].end());
      }

      memset(mt, -1, sizeof(mt));

      int lo = 1, hi = n, pos = -1;

      L = 1;

      while(hi - lo > 1){
            int md = (lo + hi) >> 1;
            R = md;
            if(ok())
                  hi = md - 1, pos = md;
            else
                  lo = md + 1;
      }

      if(pos == -1){
            cout << 0 << endl;
            return 0;
      }

      ans += n - pos + 1;

      if(mt[L] != -1){
            mt[mt[L]] = -1;
      }

      memset(used, 0, sizeof(used));

      int pt = pos;

      for(int i = 2; i <= n - m + 1; i ++){
            int lo = 1, hi = i;
            L = i, R = pt;
            while(pt <= n && !check())
                  pt ++, R = pt;
            ans += n - pt + 1;
            if(mt[L] != -1){
                  mt[mt[L]] = -1;
            }
      }

      printf("%d", ans);
}

Compilation message (stderr)

marriage.cpp: In function 'int main()':
marriage.cpp:111:17: warning: unused variable 'lo' [-Wunused-variable]
             int lo = 1, hi = i;
                 ^~
marriage.cpp:111:25: warning: unused variable 'hi' [-Wunused-variable]
             int lo = 1, hi = i;
                         ^~
marriage.cpp:67:12: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
       scanf("%d %d %d", &n, &m, &k);
       ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
marriage.cpp:71:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
             scanf("%d %d", &a, &b);
             ~~~~~^~~~~~~~~~~~~~~~~

• Subtask 1: 66 / 100