update

bailian/1088.ski/main.cc

@@ -13,7 +13,7 @@ struct Grid {
   int r;
   int c;
   int h;
-  bool operator<(const Grid that) const { return this->h < that.h; }
+  bool operator<(const Grid &that) const { return this->h < that.h; }
 };
 
 Grid area[N * N];

bailian/1328.radar-installation/main.cc

@@ -17,7 +17,7 @@ struct Island {
     rs = x - dx;
     re = x + dx;
   }
-  bool operator<(const Island that) { return this->rs < that.rs; }
+  bool operator<(const Island &that) { return this->rs < that.rs; }
 };
 
 int main() {

bailian/4110.santa-claus-gifts/main.cc

@@ -8,7 +8,7 @@ const double eps = 1e-6;
 struct Candy {
   int v;
   int w;
-  bool operator<(const Candy that) const {
+  bool operator<(const Candy &that) const {
     return double(this->v) / this->w - double(that.v) / that.w > eps;
   }
 };

poj/2373.dividing-the-path/main.cc

@@ -0,0 +1,68 @@
+#include <cstdio>
+#include <cstring>
+#include <queue>
+
+using namespace std;
+
+const int INF = 1 << 30;
+const int MAXL = 1000000;
+const int MAXN = 1000;
+int dp[MAXL + 1];
+int has_cow[MAXL + 1];
+int N, L, A, B;
+
+// If f(x) means the min cnt of sprinklers to cover [0...x], then we have
+// f(x) = INF, if x is odd
+//      = INF, if x < 2A
+//      = INF, if has_cow[x]
+//      = 1, if 2A <= x <= 2B and !has_cow[x]
+//      = min{f(y): x - 2B <= y <= x - 2A} + 1, if 2B < x and !has_cow[y]
+
+struct Fx {
+  int x;
+  int f;
+  Fx(int x = 0, int f = 0) : x(x), f(f) {}
+  bool operator<(const Fx &that) const { return this->f > that.f; }
+};
+
+int main() {
+  scanf("%d %d %d %d", &N, &L, &A, &B);
+  A <<= 1, B <<= 1;
+  for (int i = 0; i < N; i++) {
+    int s, e;
+    scanf("%d %d", &s, &e);
+    has_cow[s + 1]++;
+    has_cow[e]--;
+  }
+  for (int i = 0, cows = 0; i <= L; i++) {
+    dp[i] = INF;
+    cows += has_cow[i];
+    has_cow[i] = 0 < cows;
+  }
+  priority_queue<Fx> pq;
+  for (int x = A; x <= B; x += 2) {
+    if (!has_cow[x]) {
+      dp[x] = 1;
+      // Ensure that for each x, the y in pq has y <= x - A
+      if (x <= B + 2 - A) pq.push(Fx{x, 1});
+    }
+  }
+  for (int x = B + 2; x <= L; x += 2) {
+    if (!has_cow[x]) {
+      Fx fx;
+      while (!pq.empty()) {
+        fx = pq.top();
+        if (fx.x < x - B)
+          pq.pop();
+        else
+          break;
+      }
+      if (!pq.empty()) dp[x] = fx.f + 1;
+    }
+    // Push next Fx to queue.
+    if (dp[x + 2 - A] != INF) pq.push(Fx(x + 2 - A, dp[x + 2 - A]));
+  }
+  int cnt = dp[L] == INF ? -1 : dp[L];
+  printf("%d\n", cnt);
+  return 0;
+}

poj/3190.stall-reservations/main.cc

@@ -8,7 +8,7 @@ struct Cow {
   int i;
   int s;
   int e;
-  bool operator<(const Cow that) const { return this->s < that.s; }
+  bool operator<(const Cow &that) const { return this->s < that.s; }
 };
 
 struct Stall {