285 lines
3.5 KiB
Markdown
285 lines
3.5 KiB
Markdown
# Go 语言 ACM 格式输入输出教程
|
||
|
||
## 基础输入函数
|
||
|
||
使用 `fmt.Scan` 系列函数（不使用 bufio 缓冲区）：
|
||
|
||
| 函数 | 说明 |
|
||
|------|------|
|
||
| `fmt.Scan(&a)` | 读取一个值，以空格/换行分隔 |
|
||
| `fmt.Scanf("%d", &a)` | 带格式说明符读取 |
|
||
| `fmt.Scanln(&a)` | 读取一行，以换行结束 |
|
||
| `fmt.Sscan(str, &a)` | 从字符串读取 |
|
||
|
||
---
|
||
|
||
## 示例 1：单行读取两个整数
|
||
|
||
**输入：**
|
||
```
|
||
3 5
|
||
```
|
||
|
||
**代码：**
|
||
```go
|
||
package main
|
||
|
||
import "fmt"
|
||
|
||
func main() {
|
||
var a, b int
|
||
fmt.Scan(&a, &b)
|
||
fmt.Println(a + b)
|
||
}
|
||
```
|
||
|
||
---
|
||
|
||
## 示例 2：先给 n，再读 n 个数
|
||
|
||
**输入：**
|
||
```
|
||
5
|
||
1 2 3 4 5
|
||
```
|
||
|
||
**代码：**
|
||
```go
|
||
package main
|
||
|
||
import "fmt"
|
||
|
||
func main() {
|
||
var n int
|
||
fmt.Scan(&n)
|
||
|
||
arr := make([]int, n)
|
||
for i := 0; i < n; i++ {
|
||
fmt.Scan(&arr[i])
|
||
}
|
||
|
||
// 计算总和
|
||
sum := 0
|
||
for _, v := range arr {
|
||
sum += v
|
||
}
|
||
fmt.Println(sum)
|
||
}
|
||
```
|
||
|
||
---
|
||
|
||
## 示例 3：多行输入，每行两个数
|
||
|
||
**输入：**
|
||
```
|
||
1 2
|
||
3 4
|
||
5 6
|
||
```
|
||
|
||
**代码：**
|
||
```go
|
||
package main
|
||
|
||
import (
|
||
"fmt"
|
||
"io"
|
||
)
|
||
|
||
func main() {
|
||
var a, b int
|
||
for {
|
||
_, err := fmt.Scan(&a, &b)
|
||
if err == io.EOF {
|
||
break
|
||
}
|
||
fmt.Println(a + b)
|
||
}
|
||
}
|
||
```
|
||
|
||
---
|
||
|
||
## 示例 4：多组测试数据（EOF 结束）
|
||
|
||
**输入：**
|
||
```
|
||
3
|
||
1 2 3
|
||
2
|
||
4 5
|
||
```
|
||
|
||
**代码：**
|
||
```go
|
||
package main
|
||
|
||
import (
|
||
"fmt"
|
||
"io"
|
||
)
|
||
|
||
func main() {
|
||
for {
|
||
var n int
|
||
_, err := fmt.Scan(&n)
|
||
if err == io.EOF {
|
||
break
|
||
}
|
||
|
||
sum := 0
|
||
for i := 0; i < n; i++ {
|
||
var x int
|
||
fmt.Scan(&x)
|
||
sum += x
|
||
}
|
||
fmt.Println(sum)
|
||
}
|
||
}
|
||
```
|
||
|
||
---
|
||
|
||
## 示例 5：读取字符串
|
||
|
||
**输入：**
|
||
```
|
||
hello world
|
||
```
|
||
|
||
**代码：**
|
||
```go
|
||
package main
|
||
|
||
import "fmt"
|
||
|
||
func main() {
|
||
var s string
|
||
fmt.Scan(&s) // 只读到空格前
|
||
fmt.Println(s) // 输出: hello
|
||
|
||
// 读取整行
|
||
fmt.Scanln() // 清除换行符
|
||
var line string
|
||
fmt.Scanln(&line)
|
||
fmt.Println(line) // 输出: world
|
||
}
|
||
```
|
||
|
||
---
|
||
|
||
## 示例 6：特定结束符（输入 0 结束）
|
||
|
||
**输入：**
|
||
```
|
||
1
|
||
2
|
||
3
|
||
0
|
||
```
|
||
|
||
**代码：**
|
||
```go
|
||
package main
|
||
|
||
import "fmt"
|
||
|
||
func main() {
|
||
for {
|
||
var n int
|
||
fmt.Scan(&n)
|
||
if n == 0 {
|
||
break
|
||
}
|
||
fmt.Println(n * 2)
|
||
}
|
||
}
|
||
```
|
||
|
||
---
|
||
|
||
## 示例 7：读取不定长行（空格分隔）
|
||
|
||
**输入：**
|
||
```
|
||
1 2 3 4 5
|
||
```
|
||
|
||
**代码：**
|
||
```go
|
||
package main
|
||
|
||
import (
|
||
"bufio"
|
||
"fmt"
|
||
"os"
|
||
"strconv"
|
||
"strings"
|
||
)
|
||
|
||
func main() {
|
||
scanner := bufio.NewScanner(os.Stdin)
|
||
scanner.Scan()
|
||
line := scanner.Text()
|
||
|
||
parts := strings.Fields(line)
|
||
for _, s := range parts {
|
||
n, _ := strconv.Atoi(s)
|
||
fmt.Print(n, " ")
|
||
}
|
||
fmt.Println()
|
||
}
|
||
```
|
||
|
||
---
|
||
|
||
## 常用输出格式
|
||
|
||
```go
|
||
// 换行输出
|
||
fmt.Println(a, b)
|
||
|
||
// 空格分隔不换行
|
||
fmt.Print(a, " ", b)
|
||
|
||
// 格式化输出
|
||
fmt.Printf("%d %d\n", a, b)
|
||
|
||
// 拼接字符串输出
|
||
fmt.Println(strings.Join(strs, " "))
|
||
```
|
||
|
||
---
|
||
|
||
## 练习模板
|
||
|
||
```go
|
||
package main
|
||
|
||
import (
|
||
"fmt"
|
||
"io"
|
||
)
|
||
|
||
func main() {
|
||
// 在这里写你的代码
|
||
var n int
|
||
if _, err := fmt.Scan(&n); err == io.EOF {
|
||
return
|
||
}
|
||
|
||
// 处理逻辑
|
||
fmt.Println(n)
|
||
}
|
||
```
|
||
|
||
---
|
||
|
||
## 注意事项
|
||
|
||
1. **输入输出效率**：纯 `fmt.Scan` 对于大量数据（>10^5）会较慢
|
||
2. **换行符处理**：`fmt.Scan` 会自动跳过空格和换行
|
||
3. **EOF 检测**：用 `io.EOF` 判断输入结束
|
||
4. **类型匹配**：确保变量类型与输入格式匹配
|