题解 | 校门外的树

#include <stdio.h>

int main() {
    int L, M;
    scanf("%d %d", &L, &M);
    int removed[10001] = { 0 };//标记被移除的树，初始为0（未移除状态）
    int count = 0;//记录被移除的树的总数

    for (int i = 0; i < M; i++) {
        int l, r;
        scanf("%d %d", &l, &r);
        //标记当前区域的树为已经移除
        for (int j = l; j <= r; j++) {
            if (!removed[j]) {
                removed[j] = 1;
                count++;
            }
        }
    }
    //剩余树的数量=总树数-被移除的树数
    int remaining = (L + 1) - count;
    printf("%d", remaining);
    return 0;
}