dp

Author: hxzhao527

src/array/no_class.rs

@@ -206,11 +206,50 @@ pub fn solve_sudoku(_board: &mut Vec<Vec<char>>) {
     todo!()
 }
 
+/// [1793. 好子数组的最大分数](https://leetcode.cn/problems/maximum-score-of-a-good-subarray/?envType=daily-question&envId=2024-03-19)
+/// 
+/// 思路:
+/// 1. 在不改变最小值的前提下, 延展最多的区间
+/// 2. 然后对比这些区间
+pub fn maximum_score(nums: Vec<i32>, k: i32) -> i32 {
+    unimplemented!("暂时不知道怎么解")
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
     use crate::vec2;
 
+    #[test]
+    fn test_maximum_score(){
+        struct Testcase{
+            nums: Vec<i32>,
+            k: i32,
+            expect: i32,
+        }
+        vec![
+            Testcase{
+                nums: vec![1, 4, 3, 7, 4, 5],
+                k: 3,
+                expect: 15,
+            },
+            Testcase{
+                nums: vec![5, 5, 4, 5, 4, 1, 1, 1],
+                k: 0,
+                expect: 20,
+            },
+            Testcase{
+                nums: vec![8182,1273,9847,6230,52,1467,6062,726,4852,4507,2460,2041,500,1025,5524],
+                k: 8,
+                expect: 9014
+            }
+        ].into_iter().enumerate().for_each(|(idx, testcase)|{
+            let Testcase{nums, k, expect} = testcase;
+            let actual = maximum_score(nums, k);
+            assert_eq!(expect, actual, "case {} failed", idx);
+        });
+    }
+
     #[test]
     #[ignore = "暂时不知道怎么解"]
     fn test_solve_sudoku() {

src/array/ser/binary_search.rs

@@ -563,7 +563,7 @@ where
 /// 要求序列满足 `[from, x]` cmp 返回 true, `[x+1, end]` 返回 false
 /// 即一开始必须时 true
 ///
-/// 返回的 `I` 不保证 `cmp(I) == true`
+/// 返回的 `I` 不保证 `cmp(I) == false`
 /// 这个函数保证的是 `(I, end]` cmp不会返回true, `(I, end]` 可能是空
 ///
 /// 做了防溢出, `from`和`end`可以是0, 即传入索引
@@ -623,10 +623,100 @@ pub fn min_capability(nums: Vec<i32>, k: i32) -> i32 {
     min
 }
 
+
+/// [2529. 正整数和负整数的最大计数](https://leetcode.cn/problems/maximum-count-of-positive-integer-and-negative-integer)
+/// 
+/// 注意: 0 既不是正整数也不是负整数
+/// 
+/// 思路: 利用单调性, 找到第一个正整数和最后一个负整数, 然后计算各自的长度
+pub fn maximum_count(nums: Vec<i32>) -> i32 {
+    let first_positive = {
+        let tmp = first_occur(0, nums.len()-1, |i| nums[i] > 0);
+        if tmp == 0{
+            if nums[0] > 0{
+                0i32
+            } else {
+                1i32
+            }
+        } else if tmp == nums.len(){
+            nums.len() as i32
+        } else {
+            tmp as i32
+        }
+
+    };
+    let last_negative = {
+        let tmp = last_occur(0, nums.len()-1, |i| nums[i] < 0);
+        if tmp == 0 {
+            if nums[0] < 0{
+                1i32
+            } else {
+                0i32
+            }
+        } else if tmp == nums.len(){
+            nums.len() as i32
+        } else {
+            tmp as i32 + 1
+        }
+    };
+    
+    let pos_len = nums.len() as i32 - first_positive;
+    let neg_len = last_negative;
+
+    pos_len.max(neg_len)
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
 
+    #[test]
+    fn test_maximum_count(){
+        struct TestCase{
+            name: &'static str,
+            nums: Vec<i32>,
+            expect: i32,
+        }
+
+        vec![
+            TestCase{
+                name: "basic",
+                nums: vec![-5, -4, -3, -2, -1, 1, 2, 3, 4, 5],
+                expect: 5,
+            },
+            TestCase{
+                name: "basic 2",
+                nums: vec![-5, -4, -3, -2, -1, 0, 1, 2, 3, 4, 5],
+                expect: 5,
+            },
+            TestCase{
+                name: "basic 3",
+                nums: vec![1, 2, 3, 4, 5],
+                expect: 5,
+            },
+            TestCase{
+                name: "basic 4",
+                nums: vec![-5, -4, -3, -2, -1],
+                expect: 5,
+            },
+            TestCase{
+                name: "basic 5",
+                nums: vec![0, 1, 2, 3, 4, 5],
+                expect: 5,
+            },
+            TestCase{
+                name: "basic 6",
+                nums: vec![-5, -4, -3, -2, -1, 0],
+                expect: 5,
+            },
+        ]
+        .iter()
+        .for_each(|TestCase{name, nums, expect}|{
+            let actual = maximum_count(nums.to_vec());
+            assert_eq!(*expect, actual, "{} failed", name);
+        });
+    }
+
     #[test]
     fn test_min_capability() {
         struct TestCase {

src/dp/no_class.rs

@@ -338,13 +338,16 @@ pub fn num_factored_binary_trees(mut arr: Vec<i32>) -> i32 {
     result as i32
 }
 
-
-
 #[cfg(test)]
 mod test {
     use super::*;
     use crate::vec2;
 
+    #[test]
+    fn test_combination_sum4(){
+
+    }
+
     #[test]
     fn test_num_factored_binary_trees() {
         struct TestCase {

src/dp/ser.rs

@@ -10,4 +10,5 @@ pub mod stair;
 pub mod stock;
 pub mod tree;
 pub mod path;
-pub mod rob;
+pub mod rob;
+pub mod combination;

src/dp/ser/combination.rs

@@ -0,0 +1,66 @@
+//! 组合问题
+
+/// [377. 组合总和 Ⅳ](https://leetcode.cn/problems/combination-sum-iv)
+///
+/// 思路:
+/// 整体问题可以变成f(n) = f(n-nums[0]) + f(n-nums[1]) + ... + f(n-nums[i])
+/// 但是这种朴素的递归操作, 会因为重复计算, 使整体的计算规模扩大
+///
+/// 可以和 [70. 爬楼梯](https://leetcode-cn.com/problems/climbing-stairs/) 一样, 用dp来解决
+///
+/// 起点一定是0, 从0开始, 递推到target
+pub fn combination_sum4(nums: Vec<i32>, target: i32) -> i32 {
+    let mut dp = vec![0; target as usize + 1];
+    dp[0] = 1;
+    for i in 1..=target {
+        for &num in nums.iter() {
+            if i >= num {
+                dp[i as usize] += dp[(i - num) as usize];
+            }
+        }
+    }
+    dp[target as usize]
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use crate::vec2;
+
+    #[test]
+    fn test_combination_sum4() {
+        struct TestCase {
+            nums: Vec<i32>,
+            target: i32,
+            expected: i32,
+        }
+
+        vec![
+            TestCase {
+                nums: vec![1, 2, 3],
+                target: 4,
+                expected: 7,
+            },
+            TestCase {
+                nums: vec![9],
+                target: 3,
+                expected: 0,
+            },
+        ]
+        .into_iter()
+        .enumerate()
+        .for_each(
+            |(
+                idx,
+                TestCase {
+                    nums,
+                    target,
+                    expected,
+                },
+            )| {
+                let actual = combination_sum4(nums, target);
+                assert_eq!(expected, actual, "case {} failed", idx);
+            },
+        );
+    }
+}