P1868 饥饿的奶牛

R73067558

Luogu/P1868/P1868.cpp

@@ -0,0 +1,39 @@
+#include <iostream>
+#include <limits>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 1.5e5 + 5,
+          M = 3e6 + 5;
+
+int n, f[M], e[M];
+int l = std::numeric_limits<int>::max(),
+    r = std::numeric_limits<int>::min();
+std::pair<int, int> a[N];
+bool vis[M];
+
+int main() {
+    std::ios::sync_with_stdio(false);
+
+    cin >> n;
+    for (int i = 1, x, y; i <= n; i++) {
+        cin >> x >> y;
+        r = std::max(r, y);
+        e[x] = y;
+        vis[x] = true;
+    }
+
+    for (int i = r; i; i--) {
+        if (vis[i]) {
+            f[i] = std::max(f[i + 1], f[e[i] + 1] + (e[i] - i + 1));
+        } else {
+            f[i] = f[i + 1];
+        }
+    }
+
+    cout << f[1] << endl;
+
+    return 0;
+}