1582. Special Positions in a Binary Matrix
Given an m x n binary matrix mat, return the number of special positions in mat.
A position (i, j) is called special if mat[i][j] == 1 and all other elements in row i and column j are 0 (rows and columns are 0-indexed).
impl Solution {
pub fn num_special(mat: Vec<Vec<i32>>) -> i32 {
let mut ans = 0;
for r in 0..mat.len() {
let c = Self::check_row(&mat, r);
if c >= 0 && Self::check_col(&mat, r, c as usize) {
ans += 1;
}
}
ans
}
fn check_row(mat: &Vec<Vec<i32>>, index: usize) -> i32 {
let mut ans = -1_i32;
for c in 0..mat[0].len() {
if mat[index][c] == 1 {
if ans >= 0 {
return -1;
} else {
ans = c as i32;
}
}
}
ans
}
fn check_col(mat: &Vec<Vec<i32>>, current_row: usize, current_col: usize) -> bool {
for r in 0..mat.len() {
if mat[r][current_col] == 1 && r != current_row {
return false;
}
}
true
}
}