Bài tập C - Sắp xếp mảng Struct trong C

#include<stdio.h>
#define MAX 50

struct city {
    char name[50];
    long int population;
    float income;
} ct[MAX]; /* khai bao mang cac ctruct */

int main() {
    int i, n, mp, mi, maxPopulation, maxIncome;
    float rate;
    mp = mi = -1;
    maxPopulation = maxIncome = 0;

    printf("Nhap so thanh pho: ");
    scanf("%d", &n);

    for (i = 0; i < n; i++) {
        printf("\nNhap chi tiet thanh pho thu %d: \n", i + 1);

        printf("Nhap ten thanh pho: ");
        scanf("%s", &ct[i].name);

        printf("Nhap tong so dan: ");
        scanf("%ld", &ct[i].population);

        printf("Nhap tong thu nhap: ");
        scanf("%f", &ct[i].income);
    }

    for (i = 0; i < n; i++) {
    	// tim thanh pho co dan so dong nhat
        if (ct[i].population >= maxPopulation) {
            maxPopulation = ct[i].population;
            mp++;
        }
        // tim thanh pho co thong thu nhap cao nhat
        if (ct[i].income > maxIncome) {
            maxIncome = ct[i].income;
            mi++;
        }
    }

    printf("\nThanh pho co dan so dong nhat: %s", ct[mp].name);
    printf("\nThanh pho co tong thu nhap cao nhat: %s", ct[mi].name);

    return (0);
}