Print matrix in snake pattern from the last column in C Programming.

In C, printing a matrix in snake pattern from the last column means traversing the matrix row by row, alternating the direction of column traversal. For odd-numbered rows (index 0, 2, 4...), we print from right to left, and for even-numbered rows (index 1, 3, 5...), we print from left to right.

Syntax

for (int i = 0; i < n; i++) {
    if (i % 2 == 0) {
        // Even rows: right to left
        for (int j = n - 1; j >= 0; j--) {
            printf("%d ", arr[i][j]);
        }
    } else {
        // Odd rows: left to right
        for (int j = 0; j < n; j++) {
            printf("%d ", arr[i][j]);
        }
    }
}

Example

Here's a complete program that demonstrates snake pattern printing starting from the last column −

#include <stdio.h>

int main() {
    int n = 4;
    int arr[4][4] = {
        {100, 99, 98, 97},
        {93, 94, 95, 96},
        {92, 91, 90, 89},
        {85, 86, 87, 88}
    };
    
    printf("Matrix:
");
    for (int i = 0; i < n; i++) {
        for (int j = 0; j < n; j++) {
            printf("%3d ", arr[i][j]);
        }
        printf("
");
    }
    
    printf("\nSnake pattern from last column: ");
    for (int i = 0; i < n; i++) {
        if (i % 2 == 0) {
            // Even rows (0, 2, 4...): print right to left
            for (int j = n - 1; j >= 0; j--) {
                printf("%d ", arr[i][j]);
            }
        } else {
            // Odd rows (1, 3, 5...): print left to right
            for (int j = 0; j < n; j++) {
                printf("%d ", arr[i][j]);
            }
        }
    }
    printf("
");
    
    return 0;
}

Matrix:
100  99  98  97
 93  94  95  96
 92  91  90  89
 85  86  87  88

Snake pattern from last column: 97 98 99 100 93 94 95 96 89 90 91 92 85 86 87 88

How It Works

• The algorithm uses the modulo operator i % 2 to determine the traversal direction
• For even-indexed rows (0, 2, 4...), it starts from the last column and moves left
• For odd-indexed rows (1, 3, 5...), it starts from the first column and moves right
• This creates a snake-like zigzag pattern through the matrix

Conclusion

The snake pattern traversal from the last column efficiently prints matrix elements in a zigzag manner. This technique is useful in various matrix manipulation problems and demonstrates how simple conditional logic can create complex traversal patterns.