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Author: Zhenghao-Liu

0000.test_project/bit.h

@@ -0,0 +1,47 @@
+#ifndef BIT
+#define BIT
+
+#include<vector>
+using namespace std;
+
+class bit {
+private:
+    vector<int> t;
+    int n;
+public:
+    bit() {
+        t.clear();
+        n=0;
+    }
+
+    bit(int n) {
+        t=vector<int>(n+1);
+        this->n=n;
+    }
+
+    int lowbit(int x)
+    {
+        return x&(-x);
+    }
+
+    void add(int x,int k)
+    {
+        for (;x<=n;x+=lowbit(x))
+            t.at(x)+=k;
+    }
+
+    int ask(int x)
+    {
+        int ans=0;
+        for (;x>0;x-=lowbit(x))
+            ans+=t.at(x);
+        return ans;
+    }
+
+    int interval_sum(int x,int y)
+    {
+        return ask(y)-ask(x-1);
+    }
+};
+
+#endif