Submission #121258

#	Time	Username	Problem	Language	Result	Execution time	Memory
121258		win11905	Flood (IOI07_flood)	C++11	10 / 100	1232 ms	34672 KiB

flood

#include <bits/stdc++.h>
#define pii pair<int, int>
#define x first
#define y second
using namespace std;

const int N = 1e5;

int n, m;
int x[N], y[N];
int s[N<<1], t[N<<1];
int za[N<<1], zb[N<<1];
bitset<4> state[N];
int idx;
map<pii, int> Mp;
vector<int> coor;

int par[N<<2];

int lv[N>>1];
vector<int> g[N>>1];

int get(int x) { return lower_bound(coor.begin(), coor.end(), x) - coor.begin(); }

int find(int u) { return par[u] = par[u] == u ? u : find(par[u]); }

void merge(int a, int b, int c, int d) {
    int u = Mp[pii(a, b)], v = Mp[pii(c, d)];
    par[find(u)] = find(v);
}

int main() {
    iota(par, par+(N<<1), 0);
    scanf("%d", &n);
    int mnx = 1e9, st;
    for(int i = 0; i < n; ++i) {
        scanf("%d %d", x+i, y+i);
        Mp[pii(x[i], y[i])] = ++idx;
        Mp[pii(x[i]+1, y[i])] = ++idx;
        Mp[pii(x[i], y[i]+1)] = ++idx;
        Mp[pii(x[i]+1, y[i]+1)] = ++idx;
        if(x[i] < mnx) mnx = x[i], st = i;
    }
    scanf("%d", &m);
    for(int i = 0; i < m; ++i) {
        scanf("%d %d", s+i, t+i), s[i]--, t[i]--;
        if(x[s[i]] != x[t[i]]) {
            if(x[s[i]] > x[t[i]]) swap(s[i], t[i]);
            state[s[i]][1] = state[t[i]][3] = true;
            merge(x[s[i]]+1, y[s[i]], x[t[i]], y[t[i]]);
            merge(x[s[i]]+1, y[s[i]]+1, x[t[i]], y[t[i]]+1);            
        } else {
            if(y[s[i]] > y[t[i]]) swap(s[i], t[i]);
            state[s[i]][0] = state[t[i]][2] = true;
            merge(x[s[i]], y[s[i]]+1, x[t[i]], y[t[i]]);
            merge(x[s[i]]+1, y[s[i]]+1, x[t[i]]+1, y[t[i]]);
        }
    }
    for(int i = 0; i < n; ++i) {
        if(!state[i][0]) merge(x[i], y[i]+1, x[i]+1, y[i]+1);
        if(!state[i][1]) merge(x[i]+1, y[i], x[i]+1, y[i]+1);
        if(!state[i][2]) merge(x[i], y[i], x[i]+1, y[i]);
        if(!state[i][3]) merge(x[i], y[i], x[i], y[i]+1);
    }
    for(int i = 0; i < m; ++i) {
        int a, b;
        if(x[s[i]] != x[t[i]]) 
            a = find(Mp[pii(x[s[i]]+1, y[s[i]])]), b = find(Mp[pii(x[s[i]]+1, y[s[i]]+1)]);
        else 
            a = find(Mp[pii(x[s[i]], y[s[i]]+1)]), b = find(Mp[pii(x[s[i]]+1, y[s[i]]+1)]);
        za[i] = a, zb[i] = b;
        coor.emplace_back(a), coor.emplace_back(b);
    }
    int start = find(Mp[pii(x[st], y[st])]);
    lv[start] = 1;
    Mp.clear();
    sort(coor.begin(), coor.end());
    coor.resize(unique(coor.begin(), coor.end()) - coor.begin());
    start = get(start);
    for(int i = 0; i < m; ++i) za[i] = get(za[i]), zb[i] = get(zb[i]), g[za[i]].emplace_back(i), g[zb[i]].emplace_back(i);
    queue<int> Q; Q.emplace(start);
    vector<int> ans;
    while(!Q.empty()) {
        int u = Q.front(); Q.pop();
        for(int x : g[u]) {
            int v = za[x] ^ zb[x] ^ u;
            if(lv[v] == 0) lv[v] = lv[u] + 1, Q.emplace(v);
            if(lv[v] != lv[u] + 1 && lv[v] != lv[u] - 1) ans.emplace_back(x);
        } 
    }
    sort(ans.begin(), ans.end());
    int z = (int)ans.size() >> 1;
    printf("%d\n", z);
    for(int i = 0; i < z; ++i) printf("%d\n", ans[i<<1|1] + 1); 
}

Compilation message (stderr)

flood.cpp: In function 'int main()':
flood.cpp:34:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d", &n);
     ~~~~~^~~~~~~~~~
flood.cpp:37:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d %d", x+i, y+i);
         ~~~~~^~~~~~~~~~~~~~~~~~~
flood.cpp:44:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d", &m);
     ~~~~~^~~~~~~~~~
flood.cpp:46:41: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d %d", s+i, t+i), s[i]--, t[i]--;
         ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 0 / 10
• Subtask 3: 0 / 10
• Subtask 4: 0 / 3
• Subtask 5: 0 / 10
• Subtask 6: 0 / 3
• Subtask 7: 0 / 3
• Subtask 8: 0 / 3
• Subtask 9: 0 / 3
• Subtask 10: 0 / 9
• Subtask 11: 0 / 9
• Subtask 12: 0 / 9
• Subtask 13: 0 / 9
• Subtask 14: 0 / 9