package q2352

import "strings"

func index(grid [][]int, col bool, i int) string {
	b := strings.Builder{}
	b.Grow(len(grid) * 3)
	for j := range grid {
		var num int
		switch {
		case col: // ith col
			num = grid[j][i]
		default: // ith row
			num = grid[i][j]
		}

		for range 3 {
			b.WriteByte(byte(num % 256))
			num >>= 8
		}
	}
	return b.String()
}

func equalPairs(grid [][]int) int {
	idx := make(map[string]int, len(grid))
	nEq := 0
	for row := range grid {
		s := index(grid, false, row)
		idx[s]++
	}
	for col := range grid {
		s := index(grid, true, col)
		nEq += idx[s]
	}
	return nEq
}

var _ = equalPairs