I've got AC! The main observation is that no two queens can be in the same row or column.
Thus, we make an array perm[i], which stands for queen in the ith row and perm[i]th column. The problem is to find the number of permutations, which differs from the initial by 3 elements and check for each possibility whether we have conflicts on the diagonals. perm[i] is the initial permutation. I hope this hint was helpful!

I also got WA for test 4.....so I started to try some self made test cases.....and I came across this one :
5 4
2 0 1 3
My output : NO.
Correct Output should be YES.

I will have to rethink my approach.....maybe you have the same problem as well.

case 3 3 1 2 3 helped me in test 4.
But anyway it's better to write your own test case generator.

Edited by author 18.04.2020 04:47

7 4
2 5 7 5

First i did not understand this problem.but your suggestions help me.thanks!!!And it is really very practical, realistic and easy problem!!

No comments

Worm can move both left and right. Stop for a while and think about it.

Just take two books and try - you will find answer immediately

I fully agree with you.How could the answer for sample input be 2.

Edited by author 02.10.2020 16:52

n=0
Answer 10

Ok, looks like in my case the format of input data in tests #2 and #6 is differ from the one in the example. Accepted Go code is:


package main

import (
    "fmt"
    "sort"
)

type city struct {
    n, x, y int
}

func main() {
    var n int
    fmt.Scan(&n)
    m := make([]city, n)

    for i := 0; i < n; i++ {
        m[i].n = i + 1
        fmt.Scan(&m[i].x, &m[i].y)
    }

    sort.Slice(m, func(i, j int) bool {
        if m[i].x < m[j].x {
            return true
        }
        return false
    })

        for i := 0; i < n; i += 2 {
        fmt.Println(m[i].n, m[i+1].n)
    }
}


time:   0.14
memory: 2 044 КB


Edited by author 29.09.2020 01:10

4
-1 -2 -3 -4
-5 0 -7 -8
-9 -1 -127 -100
-3 -4 -7 -1

I have WA on tc 4 too and am unable to figure it out. Some help?

(my solution provide 4 answers at all: infinity, 0, 1, 2)

.

Edited by author 24.09.2020 17:19

looks like "aaaa" answer should be full string.

input: aaaa
output : aaaa

Yes