Problem:
Range Sum Query

Write a program which manipulates a sequence A = {a1, a2, . . . , an} with the following operations:

add(i, x): add x to ai.

getSum(s, t): print the sum of as, as+1,...,at.

Note that the initial values of ai (i = 1, 2, . . . , n) are 0.

Input

n q
com1 x1 y1
com2 x2 y2
...
comq xq yq

In the first line, n (the number of elements in A) and q (the number of queries) are given. Then, q queries are given where com represents the type of queries. '0' denotes add(xi, yi) and '1' denotes getSum(xi, yi).

Output

For each getSum operation, print the sum in a line.

Constraints

1 ≤ n ≤ 100000

1 ≤ q ≤ 100000

If comi is 0, then 1 ≤ xi ≤ n, 0 ≤ yi ≤ 1000.

If comi is 1, then 1 ≤ xi ≤ n, 1 ≤ yi ≤ n.

Sample Input 1

3 5
0 1 1
0 2 2
0 3 3
1 1 2
1 2 2

Sample Output 1

3
2

Solution in Go (judge verdict: Accepted)

package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

func main() {
	defer writer.Flush()
	n, q := ReadInt(), ReadInt()
	t := MakeSegTree(n)
	for _q := 0; _q < q; _q++ {
		if ReadInt() == 0 {
			t.Add(ReadInt()-1, ReadInt())
		} else {
			Println(t.getSum(ReadInt()-1, ReadInt()))
		}
	}
}

type SegTree []int

func MakeSegTree(n_ int) SegTree {
	n := 1
	for n < n_ {
		n <<= 1
	}
	return make([]int, n<<1)
}

func (t SegTree) Add(i, x int) {
	i += len(t) >> 1
	for i > 0 {
		t[i] += x
		i >>= 1
	}
}

func (t SegTree) getSum(a, b int) int {
	return t.getSumRecur(a, b, 1, 0, len(t)>>1)
}
func (t SegTree) getSumRecur(a, b, k, l, r int) int {
	if b <= l || r <= a {
		return 0
	}
	if a <= l && r <= b {
		return t[k]
	}
	sum := 0
	sum += t.getSumRecur(a, b, k<<1, l, (l+r)>>1)
	sum += t.getSumRecur(a, b, k<<1+1, (l+r)>>1, r)
	return sum
}

var scanner = bufio.NewScanner(os.Stdin)

func init() {
	scanner.Buffer(make([]byte, 256), 1e9)
	scanner.Split(bufio.ScanWords)
}
func ReadString() string { scanner.Scan(); return scanner.Text() }
func ReadInt() int {
	a, err := strconv.Atoi(ReadString())
	if err != nil {
		panic(err)
	}
	return a
}

var writer = bufio.NewWriter(os.Stdout)

func Println(a ...interface{}) { fmt.Fprintln(writer, a...) }