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Jul 22, 2024
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feat: add solutions to lc problem: No.2094 #3304

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207 changes: 104 additions & 103 deletions solution/2000-2099/2094.Finding 3-Digit Even Numbers/README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -80,7 +80,15 @@ tags:

<!-- solution:start -->

### 方法一
### 方法一：计数 + 枚举

我们先统计 $\textit{digits}$ 中每个数字出现的次数，记录在数组或哈希表 $\textit{cnt}$ 中。

然后，我们在 $[100, 1000)$ 的范围内枚举所有的偶数，判断这个偶数的每一位数字是否都不超过 $\textit{cnt}$ 中对应的数字的次数。如果是，则将这个偶数加入答案数组中。

最后，返回答案数组。

时间复杂度 $O(k \times 10^k)$，其中 $k$ 是目标偶数的位数，本题中 $k = 3$。忽略答案的空间消耗，空间复杂度 $O(1)$。

<!-- tabs:start -->

Expand All @@ -89,17 +97,16 @@ tags:
```python
class Solution:
def findEvenNumbers(self, digits: List[int]) -> List[int]:
cnt = Counter(digits)
ans = []
counter = Counter(digits)
for i in range(100, 1000, 2):
t = []
k = i
while k:
t.append(k % 10)
k //= 10
cnt = Counter(t)
if all([counter[i] >= cnt[i] for i in range(10)]):
ans.append(i)
for x in range(100, 1000, 2):
cnt1 = Counter()
y = x
while y:
y, v = divmod(y, 10)
cnt1[v] += 1
if all(cnt[i] >= cnt1[i] for i in range(10)):
ans.append(x)
return ans
```

Expand All @@ -108,37 +115,25 @@ class Solution:
```java
class Solution {
public int[] findEvenNumbers(int[] digits) {
int[] counter = count(digits);
int[] cnt = new int[10];
for (int x : digits) {
++cnt[x];
}
List<Integer> ans = new ArrayList<>();
for (int i = 100; i < 1000; i += 2) {
int[] t = new int[3];
for (int j = 0, k = i; k > 0; ++j) {
t[j] = k % 10;
k /= 10;
for (int x = 100; x < 1000; x += 2) {
int[] cnt1 = new int[10];
for (int y = x; y > 0; y /= 10) {
++cnt1[y % 10];
}
int[] cnt = count(t);
if (check(counter, cnt)) {
ans.add(i);
boolean ok = true;
for (int i = 0; i < 10 && ok; ++i) {
ok = cnt[i] >= cnt1[i];
}
}
return ans.stream().mapToInt(Integer::valueOf).toArray();
}

private boolean check(int[] cnt1, int[] cnt2) {
for (int i = 0; i < 10; ++i) {
if (cnt1[i] < cnt2[i]) {
return false;
if (ok) {
ans.add(x);
}
}
return true;
}

private int[] count(int[] nums) {
int[] counter = new int[10];
for (int num : nums) {
++counter[num];
}
return counter;
return ans.stream().mapToInt(i -> i).toArray();
}
}
```
Expand All @@ -149,102 +144,108 @@ class Solution {
class Solution {
public:
vector<int> findEvenNumbers(vector<int>& digits) {
vector<int> counter = count(digits);
int cnt[10]{};
for (int x : digits) {
++cnt[x];
}
vector<int> ans;
for (int i = 100; i < 1000; i += 2) {
vector<int> t(3);
for (int j = 0, k = i; k > 0; ++j) {
t[j] = k % 10;
k /= 10;
for (int x = 100; x < 1000; x += 2) {
int cnt1[10]{};
for (int y = x; y; y /= 10) {
++cnt1[y % 10];
}
bool ok = true;
for (int i = 0; i < 10 && ok; ++i) {
ok = cnt[i] >= cnt1[i];
}
if (ok) {
ans.push_back(x);
}
vector<int> cnt = count(t);
if (check(counter, cnt)) ans.push_back(i);
}
return ans;
}

vector<int> count(vector<int>& nums) {
vector<int> counter(10);
for (int num : nums) ++counter[num];
return counter;
}

bool check(vector<int>& cnt1, vector<int>& cnt2) {
for (int i = 0; i < 10; ++i)
if (cnt1[i] < cnt2[i])
return false;
return true;
}
};
```

#### Go

```go
func findEvenNumbers(digits []int) []int {
counter := count(digits)
var ans []int
for i := 100; i < 1000; i += 2 {
t := make([]int, 3)
k := i
for j := 0; k > 0; j++ {
t[j] = k % 10
k /= 10
func findEvenNumbers(digits []int) (ans []int) {
cnt := [10]int{}
for _, x := range digits {
cnt[x]++
}
for x := 100; x < 1000; x += 2 {
cnt1 := [10]int{}
for y := x; y > 0; y /= 10 {
cnt1[y%10]++
}
cnt := count(t)
if check(counter, cnt) {
ans = append(ans, i)
ok := true
for i := 0; i < 10 && ok; i++ {
ok = cnt[i] >= cnt1[i]
}
}
return ans
}

func count(nums []int) []int {
counter := make([]int, 10)
for _, num := range nums {
counter[num]++
}
return counter
}

func check(cnt1, cnt2 []int) bool {
for i := 0; i < 10; i++ {
if cnt1[i] < cnt2[i] {
return false
if ok {
ans = append(ans, x)
}
}
return true
return
}
```

#### TypeScript

```ts
function findEvenNumbers(digits: number[]): number[] {
let record = new Array(10).fill(0);
for (let digit of digits) {
record[digit]++;
const cnt: number[] = Array(10).fill(0);
for (const x of digits) {
++cnt[x];
}
let ans = [];
for (let i = 100; i < 1000; i += 2) {
if (check(record, String(i))) {
ans.push(i);
const ans: number[] = [];
for (let x = 100; x < 1000; x += 2) {
const cnt1: number[] = Array(10).fill(0);
for (let y = x; y; y = Math.floor(y / 10)) {
++cnt1[y % 10];
}
let ok = true;
for (let i = 0; i < 10 && ok; ++i) {
ok = cnt[i] >= cnt1[i];
}
if (ok) {
ans.push(x);
}
}
return ans;
}
```

function check(target: Array<number>, digits: string): boolean {
let record = new Array(10).fill(0);
for (let digit of digits) {
record[digit]++;
#### JavaScript

```js
/**
* @param {number[]} digits
* @return {number[]}
*/
var findEvenNumbers = function (digits) {
const cnt = Array(10).fill(0);
for (const x of digits) {
++cnt[x];
}

for (let i = 0; i < 10; i++) {
if (record[i] > target[i]) return false;
const ans = [];
for (let x = 100; x < 1000; x += 2) {
const cnt1 = Array(10).fill(0);
for (let y = x; y; y = Math.floor(y / 10)) {
++cnt1[y % 10];
}
let ok = true;
for (let i = 0; i < 10 && ok; ++i) {
ok = cnt[i] >= cnt1[i];
}
if (ok) {
ans.push(x);
}
}
return true;
}
return ans;
};
```

<!-- tabs:end -->
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