Practical2/checkout.c


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#include <stdio.h>
#include <stdint.h>

uint32_t round_ct(uint32_t cents) {
    switch (cents % 5) {
        case 0: return cents;
        case 1: return cents - 1;
        case 2: return cents - 2;
        case 3: return cents + 2;
        case 4: return cents + 1;
    }
}

int32_t maximum_profit(uint16_t products[], uint16_t n_products, uint8_t dividers) {
    int32_t profit[n_products+1][dividers+1];
    uint16_t p, d;
    for (p = 0; p <= n_products; p++) {
        uint32_t sums[p];
        if (p == 0) {
            sums[0] = 0;
        } else {
            int16_t i;
            for (i = p-1; i >= 0; i--) {
                if (i == p-1)
                    sums[i] = products[i];
                else
                    sums[i] = products[i] + sums[i+1];
            }
        }

        for (d = 0; d <= dividers; d++) {
            if (p == 0) {
                profit[p][d] = 0;
            } else if (d == 0) {
                profit[p][d] = sums[0] - round_ct(sums[0]);
            } else {
                int32_t max = profit[p][d-1];
                uint16_t i;
                for (i = 0; i < p; i++) {
                    int32_t try = profit[i][d-1] + sums[i] - round_ct(sums[i]);
                    if (try > max)
                        max = try;
                }
                profit[p][d] = max;
            }
        }
    }

    return profit[n_products][dividers];
}

int main(void) {
    int n_products;
    int dividers;
    uint32_t sum = 0;

    scanf("%d %d", &n_products, &dividers);

    uint16_t products[n_products];
    uint16_t i;
    for (i = 0; i < n_products; i++) {
        scanf("%d", &(products[i]));
        sum += products[i];
        if (products[i] % 5 == 0) {
            n_products--;
            i--;
        }
    }

    printf("%d\n", sum - maximum_profit(products, n_products, dividers));
}