#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

double fraction(int a, int b) { return (double)a / (double)b; }

bool bissextile(int year) {
    return year % 4 == 0 && (year % 100 != 0 || year % 400 == 0);
}

double evalue(double coef[], int size, double x) {
    double res = 0;
    while (size > 0) {
        size -= 1;
        res *= x;
        res += coef[size];
    }
    return res;
}

int ecartmin(int t[], int size) {
    int min = abs(t[size - 1] - t[size - 2]);
    while (size > 2) {
        size -= 1;
        int ecart = abs(t[size - 1] - t[size - 2]);
        if (ecart < min) {
            min = ecart;
        }
    }
    return min;
}

// Returns 0 if no integer has been detected
int extraire(char str[]) {
    while (*str != '-' && (*str <= '0' || *str >= '9')) {
        if (*str == 0) {
            return 0;
        }
        str += 1;
    }

    int signe = 1 - (2 * (*str == '-'));
    str += *str == '-';

    int res = 0;
    while (*str >= '0' && *str <= '9') {
        res *= 10;
        res += *str - '0';
        str += 1;
    }
    return res * signe;
}

double sommemajo(double t[], int size) {
    int signe = 0;
    double pos = 0.;
    double neg = 0.;
    while (size > 0) {
        size -= 1;
        double x = t[size];
        if (x > 0) {
            signe += 1;
            pos += x;
        } else if (x < 0) {
            signe -= 1;
            neg += x;
        }
    }
    return (pos * (signe > 0)) + (neg * (signe < 0));
}

// Only works with ASCII
int nbdiff(char str[]) {
    int chars[126] = {0};
    while (*str) {
        chars[*str - 1] += 1;
        str += 1;
    }
    int count = 0;
    char c = 1;
    while (c < 126) {
        count += chars[c] > 0;
        c += 1;
    }
    return count;
}

bool palindromeint(int a) {
    int temp = a;
    int rev = 0;
    while (temp) {
        rev *= 10;
        rev += temp % 10;
        temp /= 10;
    }
    return a == rev;
}

// Only works with alphabetical strings
bool palindrome2(char str[]) {
    int size = strlen(str);
    while (size > 1) {
        char c1 = *str;
        c1 += ('a' - 'A') * (c1 <= 'Z');
        char c2 = str[size - 1];
        c2 += ('a' - 'A') * (c2 <= 'Z');
        if (c1 != c2) {
            return false;
        }
        str += 1;
        size -= 2;
    }
    return true;
}

int sommeentiers(char str[]) {
    int count = 0;
    while (true) {
        while (*str != '-' && (*str <= '0' || *str >= '9')) {
            if (*str == 0) {
                return count;
            }
            str += 1;
        }

        int signe = 1 - (2 * (*str == '-'));
        str += *str == '-';

        int res = 0;
        while (*str >= '0' && *str <= '9') {
            res *= 10;
            res += *str - '0';
            str += 1;
        }
        count += signe * res;
    }
}

int main() {
    printf("-2/3 = %f\n\n", fraction(-2, 3));

    printf("2004 %s bissextile\n", bissextile(2004) ? "est" : "n'est pas");
    printf("2100 %s bissextile\n\n", bissextile(2100) ? "est" : "n'est pas");

    printf("Avec x=-3.716309026, 2.5x² - 2x + 0.04=%f\n\n",
           evalue((double[3]){0.04, -2., 2.5}, 3, -3.716309026));

    printf("min([2, 5, 89, 3]) = %d\n\n", ecartmin((int[4]){2, 5, 89, 3}, 4));

    printf("Le premier nombre dans \"eia42snt-134eius34)\" est %d\n\n",
           extraire("eia42snt-134eius34)"));

    printf("sommemajo([80, -2, -1])=%f\n\n",
           sommemajo((double[3]){80., -2., -1.}, 3));

    printf("\"eia42snt-134eius34)\" a %d caractères différents\n\n",
           nbdiff("eia42snt-134eius34)"));

    printf("42 %s un palindrome\n", palindromeint(42) ? "est" : "n'est pas");
    printf("123454321 %s un palindrome\n\n",
           palindromeint(123454321) ? "est" : "n'est pas");

    printf("\"eiasnteius\" %s un palindrome\n",
           palindrome2("eiasnteius") ? "est" : "n'est pas");
    printf("\"Kayak\" %s un palindrome\n\n",
           palindrome2("Kayak") ? "est" : "n'est pas");

    printf("La somme des entiers dans \"eia42snt-134eius34)\" est %d\n",
           sommeentiers("eia42snt-134eius34)"));
}