🥺chore

Author: hppRC

snipetts/binary_indexed_tree.py

@@ -1,42 +1,47 @@
-class Bit:
-    def __init__(self, n, default=0): self.size, self.tree = n, [default] * (n + 1)
-    # get sum of [0, i]
-    def sum(self, i):
-        s = 0
+class BIT:
+    def __init__(self, li):
+        self.n, self.data = len(li) + 1, [0] + li
+        for i in range(1, self.n):
+            if i + (i & -i) < self.n: self.data[i + (i & -i)] += self.data[i]
+
+    def add(self, i, a):
+        i += 1
+        while i < self.n:
+            self.data[i] += a
+            i += i & -i
+
+    # sum of [0, i)
+    def acc(self, i):
+        res = 0
         while i > 0:
-            s += self.tree[i]
+            res += self.data[i]
             i -= i & -i
-        return s
+        return res
 
-    def add(self, i, x):
-        i = max(i, 1)
-        while i <= self.size:
-            self.tree[i] += x
-            i += i & -i
+    # sum of [l, r)
+    def get(self, l, r = None):
+        if r is None: r = l+1
+        return self.acc(r) - self.acc(l)
+
+
+# class ExBIT:
+#     def __init__(self, n):
+#         self.p = Bit(n + 1)
+#         self.q = Bit(n + 1)
+
+#     # add x to [l, r] (not [l, r)])
+#     def add(self, x, l, r=None):
+#         if r is None: r = l
+#         r += 1
+#         self.p.add(l, -x * l)
+#         self.p.add(r, x * r)
+#         self.q.add(l, x)
+#         self.q.add(r, -x)
+
+#     def sum(self, l, r):
+#         r += 1
+#         return self.p.sum(r) + self.q.sum(r) * r - self.p.sum(l) - self.q.sum(l) * l
 
-    # get sum of [l, r], or just l
-    def get(self, l, r=None):
-        if r is None: r = l
-        return self.sum(r) - self.sum(l-1)
-
-class ExBIT:
-    def __init__(self, n):
-        self.p = Bit(n + 1)
-        self.q = Bit(n + 1)
-
-    # add x to [l, r] (not [l, r)])
-    def add(self, x, l, r=None):
-        if r is None: r = l
-        r += 1
-        self.p.add(l, -x * l)
-        self.p.add(r, x * r)
-        self.q.add(l, x)
-        self.q.add(r, -x)
-
-    def sum(self, l, r):
-        r += 1
-        return self.p.sum(r) + self.q.sum(r) * r - self.p.sum(l) - self.q.sum(l) * l
-
-    def get(self, l, r=None):
-        if r is None: r = l
-        return self.sum(l, r)
+#     def get(self, l, r=None):
+#         if r is None: r = l
+#         return self.sum(l, r)