Last Day Where You Can Still Cross

Understand how to apply the union find algorithm to determine the final day one can cross a matrix before flooding blocks all land paths. This lesson guides you through managing binary grid states and movement constraints to solve the crossing problem.

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Statement

You are given two integers, rows and cols, which represent the number of rows and columns in a 1-based binary matrixA 1-based matrix has an indexing that starts from 1 instead of 0, and a binary matrix contains only binary values, i.e., 0 and 1. Therefore, a 1-based binary matrix is a matrix containing only 0s and 1s, whose indexes (for both rows and columns) start from 1.. In this matrix, each $0$ represents land, and each $1$ represents water.

Initially, on day 0, the whole matrix will just be all 0s, that is, all land. With each passing day, one of the cells of this matrix will get flooded and, therefore, will change to water, that is, from $0$ to $1$ . This continues until the entire matrix is flooded. You are given a 1-based array, waterCells, that records which cell will be flooded on each day. Each element $waterCells[i] = [r_{i},c_{i}]$ ...