Practical2/c/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;
    }
}

uint32_t minimum_payment(uint16_t products[], uint16_t n_products, uint8_t dividers) {
    uint32_t minimums[n_products+1][dividers+1];
    uint32_t last[n_products+1][dividers+1];

    uint16_t p, d, q;

    for (p = 0; p <= n_products; p++) {
        for (d = 0; d <= dividers; d++) {
            if (p == 0 || d == 0) {
                uint32_t sum = 0;
                for (q = 0; q < n_products && q < p; q++)
                    sum += products[q];
                minimums[p][d] = round_ct(sum);
                last[p][d] = sum;
            } else {
                uint16_t try1 = minimums[p-1][d] - round_ct(last[p-1][d]) + round_ct(last[p-1][d] + products[p-1]);
                uint16_t try2 = minimums[p-1][d-1] + round_ct(products[p-1]);
                if (try1 < try2) {
                    minimums[p][d] = try1;
                    last[p][d] = last[p-1][d] + products[p-1];
                } else {
                    minimums[p][d] = try2;
                    last[p][d] = products[p-1];
                }
            }
        }
    }

    return minimums[n_products][dividers];
}

int main(void) {
    int n_products;
    int dividers;
    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]));

    printf("%d\n", minimum_payment(products, n_products, dividers));
}