请求二维字符数组中连续相同字符最长长度的算法或伪代码

Alright, let's walk through how to solve this grid problem where we need to find the longest run of identical consecutive characters (either horizontal or vertical). Below is a straightforward algorithm and pseudocode that's easy to translate into C:

The core idea is to check every possible horizontal and vertical sequence in the grid, keeping track of the longest consecutive streak we find:

• Start with a maximum count of 1 (since even a single character counts as a streak of 1)
• Horizontal check: Iterate through each row, comparing each character to the one before it. Count consecutive matches and update the maximum streak whenever we find a longer one.
• Vertical check: Do the same for each column, comparing each character to the one above it. Again, update the maximum streak as needed.
• After checking all rows and columns, the maximum count will be our answer.

// Read number of test cases
READ T

FOR each test case in 1..T:
    // Read grid dimensions: n rows, m columns
    READ n, m
    
    // Initialize and populate the grid
    CREATE 2D array grid[n][m]
    FOR i from 0 to n-1:
        READ row (a string of m lowercase characters)
        FOR j from 0 to m-1:
            grid[i][j] = row[j]
    
    // Set initial maximum streak to 1 (minimum possible value)
    max_streak = 1

    // Check horizontal consecutive characters
    FOR each row i in 0..n-1:
        current_streak = 1
        FOR each column j in 1..m-1:
            IF grid[i][j] == grid[i][j-1]:
                current_streak += 1
                // Update max if current streak is longer
                IF current_streak > max_streak:
                    max_streak = current_streak
            ELSE:
                // Reset streak when characters don't match
                current_streak = 1

    // Check vertical consecutive characters
    FOR each column j in 0..m-1:
        current_streak = 1
        FOR each row i in 1..n-1:
            IF grid[i][j] == grid[i-1][j]:
                current_streak += 1
                IF current_streak > max_streak:
                    max_streak = current_streak
            ELSE:
                current_streak = 1

    // Output the result for this test case
    PRINT max_streak

Key Notes #

• We initialize max_streak to 1 to handle edge cases where all characters in the grid are unique (so the longest streak is 1).
• Separating horizontal and vertical checks keeps the logic simple and easy to debug.
• We update max_streak immediately whenever we find a longer streak to ensure we never miss the maximum value.

内容的提问来源于stack exchange，提问作者harish