Create bit-2d.cpp

data-structure/bit-2d.cpp

@@ -0,0 +1,43 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+class BIT {
+public:
+  int n;
+  vector<int> f;
+  BIT(int n) : n(n) {
+    f.resize(n + 1, 0);
+  }
+  void update(int p, int v) {
+    while (p <= n) f[p] += v, p += p & -p;
+  }
+  int pref(int p) {
+    p++;
+    int ret = 0;
+    while (p) ret += f[p], p -= p & -p;
+    return ret;
+  }
+  int range(int l, int r) {
+    return pref(r) - pref(l - 1);
+  }
+};
+
+class BIT2D {
+public:
+  int n, m;
+  vector<BIT> f;
+  BIT2D(int n, int m) : n(n) {
+    f.resize(n + 1, BIT(m));
+  }
+  void update(int p, int q, int v) {
+    while (p <= n) f[p].update(q, v), p += p & -p;
+  }
+  int pref(int p, int q) {
+    int ret = 0;
+    while (p) ret += f[p].pref(q), p -= p & -p;
+    return ret;
+  }
+  int range(int x1, int y1, int x2, int y2) {
+    return pref(x2, y2) - pref(x2, y1 - 1) - pref(x1 - 1, y2) + pref(x1 - 1, y1 - 1);
+  }
+};