10020 solved

10020.cpp

@@ -0,0 +1,85 @@
+#include <iostream>
+#include <vector>
+#include <algorithm>
+using namespace std;
+
+#define pow2(i) (1<<i)
+#define bit(i) (1<<i)
+#define isOdd(i) (i&1)
+#define isEven(i) (!(i&1))
+#define sz(i) i.size()
+#define REP(i, b, n) for (int i = b; i < n; i++)
+#define REPI(i, b, n) for (int i = b; i <= n; i++)
+#define rep(i, n) REP(i, 0, n)
+#define repi(i, n) REPI(i, 0, n)
+
+bool theTruthIsOutThere(const pair<int,int> &a, const pair<int,int> &b) {
+    if (a.first == b.first) return a.second > b.second;
+    return a.first < b.first;
+}
+
+void solve(int M, vector< pair<int,int> > &lines, vector< pair<int,int> > &result) {
+    int end = 0;
+    int index = 0;
+    bool first = true;
+    pair<int,int> tmp = make_pair(-1, -1);
+
+    while (index < sz(lines)) {
+        if (lines[index].first <= end) {
+            if (first) {
+                tmp = lines[index];
+                first = false;
+            } else if (lines[index].second > tmp.second) {
+                tmp = lines[index];
+            }
+            index++;
+        } else {
+            if (first)
+                break;
+            result.push_back(tmp);
+            end = tmp.second;
+            first = true;
+            if (end >= M) break;
+        }
+    }
+
+    if (!first) result.push_back(tmp);
+}
+
+int main(void) {
+    int cases, M;
+    pair<int,int> tmp;
+
+    cin >> cases;
+
+    while (cases--) {
+        cin >> M;
+        vector< pair<int,int> > lines;
+        vector< pair<int,int> > result;
+
+        while (cin >> tmp.first >> tmp.second) {
+            if (tmp.second < 0) continue;
+            if (tmp.first == 0 && tmp.second == 0) break;
+            lines.push_back(tmp);
+        }
+
+        sort (lines.begin(), lines.end(), theTruthIsOutThere);
+
+        if (lines[0].first > 0) {
+            cout << 0 << endl;
+        } else {
+            solve(M, lines, result);
+            if (result.empty() || result[result.size()-1].second < M)
+                cout << 0 << endl;
+            else {
+                cout << sz(result) << endl;
+                rep (i, sz(result))
+                    cout << result[i].first << " " << result[i].second << endl;
+            }
+        }
+
+        if (cases) cout << endl;
+    }
+
+    return 0;
+}