key比较大要用map,要注意的是go的map不是有序的,要先放到切片里面排个序再根据切片的顺序输出

package main

import (
	"bufio"
	"fmt"
	"os"
	"sort"
)

func main() {
	var t, k, v int
	in := bufio.NewReader(os.Stdin)
	sz := make(map[int]int)
	px := []int{}
	fmt.Fscan(in, &t)
	for i := 0; i < t; i++ {
		fmt.Fscan(in, &k, &v)
		sz[k] += v
	}
	for k := range sz {
		px = append(px, k)
	}
	sort.Ints(px)
	for _, v := range px {
		fmt.Println(v, sz[v])
	}
}