A five-color, in-place partitioning algorithm in O(n)-time (based on the Dutch flag algorithm).

jodhpur.c

enum Color {
    ORANGE,
    WHITE,
    RED,
    YELLOW,
    GREEN,
};

void swap(enum Color *a, enum Color *b) {
    enum Color temp;

    temp = *a;
    *a = *b;
    *b = temp;
}

// https://stackoverflow.com/a/43015749
void jodhpur(enum Color *colors, int count) {
    int orange = 0;
    int white = 0;
    int red = 0;
    int yellow = 0;
    int green = count - 1;

    while (yellow <= green) {
        switch (colors[yellow]) {
        case ORANGE:
            swap(&colors[orange], &colors[yellow]);
            orange++;
            if (white < orange) {
                white++;
            }
            if (red < orange) {
                red++;
            }
            if (yellow < orange) {
                yellow++;
            }
            break;
        case WHITE:
            swap(&colors[white], &colors[yellow]);
            white++;
            if (red < white) {
                red++;
            }
            if (yellow < white) {
                yellow++;
            }
            break;
        case RED:
            swap(&colors[red], &colors[yellow]);
            red++;
            yellow++;
            break;
        case YELLOW:
            yellow++;
            break;
        case GREEN:
            swap(&colors[green], &colors[yellow]);
            green--;
            break;
        }
    }
}