Merge branch 'master' into fix/cargo-fmt

Author: qryxip

.github/workflows/ci.yml

@@ -0,0 +1,97 @@
+name: CI
+
+on:
+  schedule:
+    - cron: '0 0 * * 6'
+  push:
+    branches:
+      - '*'
+  pull_request:
+
+jobs:
+  rustfmt:
+    strategy:
+      fail-fast: false
+      matrix:
+        toolchain:
+          - 1.42.0-x86_64-unknown-linux-gnu
+          - stable-x86_64-unknown-linux-gnu
+
+    name: Rustfmt (${{ matrix.toolchain }})
+    runs-on: ubuntu-18.04
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - name: 'Setup `${{ matrix.toolchain }}`'
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: ${{ matrix.toolchain }}
+          override: true
+          profile: minimal
+          components: rustfmt
+
+      - name: cargo-fmt
+        uses: actions-rs/cargo@v1
+        with:
+          command: fmt
+          args: --all -- --check
+
+  build:
+    strategy:
+      fail-fast: false
+      matrix:
+        toolchain:
+          - 1.42.0-x86_64-pc-windows-msvc
+          - 1.42.0-x86_64-apple-darwin
+          - 1.42.0-x86_64-unknown-linux-gnu
+          - stable-x86_64-pc-windows-msvc
+          - stable-x86_64-apple-darwin
+          - stable-x86_64-unknown-linux-gnu
+        include:
+          - { toolchain: 1.42.0-x86_64-pc-windows-msvc  , os: windows-2019 }
+          - { toolchain: 1.42.0-x86_64-apple-darwin     , os: macos-10.15  }
+          - { toolchain: 1.42.0-x86_64-unknown-linux-gnu, os: ubuntu-18.04 }
+          - { toolchain: stable-x86_64-pc-windows-msvc  , os: windows-2019 }
+          - { toolchain: stable-x86_64-apple-darwin     , os: macos-10.15  }
+          - { toolchain: stable-x86_64-unknown-linux-gnu, os: ubuntu-18.04 }
+
+    name: Build (${{ matrix.toolchain }})
+    runs-on: ${{ matrix.os }}
+
+    steps:
+      - name: Disable `core.autocrlf`
+        run: git config --global core.autocrlf false
+        if: matrix.os == 'windows-2019'
+
+      - name: Checkout
+        uses: actions/checkout@v2
+
+      - name: 'Setup `${{ matrix.toolchain }}`'
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: ${{ matrix.toolchain }}
+          override: true
+          profile: minimal
+          components: clippy
+
+      - name: cargo-clippy
+        uses: actions-rs/cargo@v1
+        with:
+          command: clippy
+          args: --workspace --all-targets -- -D warnings
+
+      - name: cargo-build
+        uses: actions-rs/cargo@v1
+        with:
+          command: build
+          args: --workspace --all-targets
+
+      - name: cargo-test
+        uses: actions-rs/cargo@v1
+        with:
+          command: test
+          args: --workspace --no-fail-fast
+        env:
+          RUST_BACKTRACE: full

src/fenwicktree.rs

@@ -1 +1,60 @@
+// Reference: https://en.wikipedia.org/wiki/Fenwick_tree
+pub struct FenwickTree<T> {
+    n: usize,
+    ary: Vec<T>,
+    e: T,
+}
 
+impl<T: Clone + std::ops::AddAssign<T>> FenwickTree<T> {
+    pub fn new(n: usize, e: T) -> Self {
+        FenwickTree {
+            n: n,
+            ary: vec![e.clone(); n],
+            e: e,
+        }
+    }
+    pub fn accum(&self, mut idx: usize) -> T {
+        let mut sum = self.e.clone();
+        while idx > 0 {
+            sum += self.ary[idx - 1].clone();
+            idx &= idx - 1;
+        }
+        sum
+    }
+    /// performs data[idx] += val;
+    pub fn add<U: Clone>(&mut self, mut idx: usize, val: U)
+    where
+        T: std::ops::AddAssign<U>,
+    {
+        let n = self.n;
+        idx += 1;
+        while idx <= n {
+            self.ary[idx - 1] += val.clone();
+            idx += idx & idx.wrapping_neg();
+        }
+    }
+    /// Returns data[l] + ... + data[r - 1].
+    pub fn sum(&self, l: usize, r: usize) -> T
+    where
+        T: std::ops::Sub<Output = T>,
+    {
+        self.accum(r) - self.accum(l)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn fenwick_tree_works() {
+        let mut bit = FenwickTree::new(5, 0i64);
+        // [1, 2, 3, 4, 5]
+        for i in 0..5 {
+            bit.add(i, i as i64 + 1);
+        }
+        assert_eq!(bit.sum(0, 5), 15);
+        assert_eq!(bit.sum(0, 4), 10);
+        assert_eq!(bit.sum(1, 3), 5);
+    }
+}

src/lib.rs

@@ -10,3 +10,5 @@ mod scc;
 mod segtree;
 mod string;
 mod twosat;
+
+pub use fenwicktree::FenwickTree;