S2Q2 · Find Sum and Absolute Difference Alternately¶

⚡ Quick Reference

Type: Full I/O problem

Core idea: for odd-numbered pairs (1, 3, 5…) print the sum; for even-numbered pairs (2, 4, 6…) print the absolute difference.

n = int(input())
for i in range(1, n + 1):
    a, b = map(int, input().split(","))
    if i % 2 == 1:
        print(a + b)
    else:
        print(abs(a - b))

Key rules: - Pairs are 1-indexed: pair 1, 2, 3, … - Odd pair number → sum - Even pair number → absolute difference - Input is comma-separated (no spaces)

Problem Statement¶

Problem (I/O type)

Read n comma-separated pairs. Print the sum for odd-numbered pairs and the absolute difference for even-numbered pairs.

Example:

Input

3
1,2
3,5
4,3

Output

3
2
7

Tracing the example¶

Pair #	Input	Odd or even?	Operation	Output
1	`1,2`	Odd	`1+2`	`3`
2	`3,5`	Even	`\\|3-5\\|`	`2`
3	`4,3`	Odd	`4+3`	`7`

Solution approaches¶

Pythonic (ternary)Explanatory (if-else)Using enumerateUsing lambda + map

n = int(input())
for i in range(1, n + 1):
    a, b = map(int, input().split(","))
    print(a + b if i % 2 == 1 else abs(a - b))

n = int(input())
for i in range(1, n + 1):
    a, b = map(int, input().split(","))
    if i % 2 == 1:       # odd-numbered pair
        print(a + b)
    else:                # even-numbered pair
        print(abs(a - b))

n = int(input())
pairs = [input().split(",") for _ in range(n)]
for i, (a_str, b_str) in enumerate(pairs, 1):
    a, b = int(a_str), int(b_str)
    print(a + b if i % 2 == 1 else abs(a - b))

enumerate(pairs, 1) gives 1-based pair numbers automatically.

n = int(input())
pairs = [list(map(int, input().split(","))) for _ in range(n)]
results = list(map(
    lambda pair: pair[0][0] + pair[0][1] if pair[1] % 2 == 1 else abs(pair[0][0] - pair[0][1]),
    zip(pairs, range(1, n + 1))
))
print("\n".join(map(str, results)))

zip(pairs, range(1, n+1)) pairs each input pair with its 1-based index. The lambda decides sum or abs diff. "\n".join(...) prints all results at once.

Key takeaways¶

01

1-indexed with range(1, n+1)

Using range(1, n+1) gives loop variable i starting at 1. Then i % 2 == 1 is True for odd pairs - no off-by-one adjustment needed.

02

input().split(",") for comma-separated input

When the separator is a comma (not whitespace), use split(",") explicitly. The default split() splits on any whitespace and would fail here.

03

abs() for absolute difference

abs(a - b) handles both a > b and b > a in one expression. Never write if a > b: a-b else: b-a when abs() does it cleanly.