题解 | #剩下的树#

#include <stdio.h>
#include<stdbool.h>
int main() {
    int number, count;
    scanf("%d %d", &number, &count);
    bool Arr[number];
    for (int i = 0; i <= number; i++) {
        Arr[i] = 1;
    }
    while (count--) {
        int left, right;
        scanf("%d %d\n", &left, &right);
        for (int j = left; j <= right; j++) {
            Arr[j] = 0;
        }
    }
    int sum = 0;
    for (int k = 0; k <= number; k++) {
        if (Arr[k] == 1) {
            sum++;
        }
    }
    printf("%d", sum);
    return 0;
}