帮我添加注释：帮我添加注释：#include <stdio.h> #include <string.h> #include <stdlib.h> #include <stdbool.h> #define N 1000000 int a[N], b[N]; int n = 0; int m = 0; bool check(int x) { int cnt = 0; for (i = 1; i <= n; i++) { if (a[i] < x) { continue; } cnt += 1 + (a[i] - x) / b[i]; if (cnt >= m) { return true; } } return false; } int main() { int i = 0; int t = 0; int mid = 0; printf("请输入两个整数n和m:\n"); scanf("%d %d", &n, &m); for (i = 1; i <= n; i++) { scanf("%d %d", a + i, b + i); } int l = 0; int r = 1e6; while (l < r - 1) { mid = (l + r + 1) >> 1; if (check(mid)) { l = mid; } else { r = mid - 1; } } int x = l; long long res = 0, cc = 0; for (i = 1; i <= n; i++) { if (a[i] < x) { continue; } t = (a[i] - x) / b[i] + 1; if (a[i] - (t - 1) * b[i] == x) { t--; cc++; } if (m >= t) { m -= t; res += (long long)t * (a[i] + a[i] - (t - 1) * b[i]) / 2; } else { t = m; m = 0; res += (long long)t * (a[i] + a[i] - (t - 1) * b[i]) / 2; break; } } res = res + (long long)(m < cc) * x * m; printf("%lld\n", res); return

帮我添加注释：

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stdbool.h>
#define N 1000000

int a[N], b[N]; // 定义两个数组a和b
int n = 0; // a和b数组的长度
int m = 0; // 需要选出的数的个数

// 判断是否满足选出的数的个数
bool check(int x) {
    int cnt = 0;
    for (int i = 1; i <= n; i++) {
        if (a[i] < x) {
            continue;
        }
        cnt += 1 + (a[i] - x) / b[i];
        if (cnt >= m) {
            return true;
        }
    }
    return false;
}

int main() {
    int i = 0;
    int t = 0;
    int mid = 0;

    // 输入a和b数组的长度n和需要选出的数的个数m
    printf("请输入两个整数n和m:\n");
    scanf("%d %d", &n, &m);

    // 输入n个a和b的值
    for (i = 1; i <= n; i++) {
        scanf("%d %d", a + i, b + i);
    }

    int l = 0; // 二分查找左端点
    int r = 1e6; // 二分查找右端点
    while (l < r - 1) {
        mid = (l + r + 1) >> 1; // 取中间值
        if (check(mid)) {
            l = mid; // 中间值满足条件，将左端点移动到中间值
        } else {
            r = mid - 1; // 中间值不满足条件，将右端点移动到中间值
        }
    }

    int x = l; // 选出的数的最大值
    long long res = 0, cc = 0;
    for (i = 1; i <= n; i++) {
        if (a[i] < x) {
            continue;
        }
        t = (a[i] - x) / b[i] + 1;
        if (a[i] - (t - 1) * b[i] == x) {
            t--;
            cc++;
        }
        if (m >= t) {
            m -= t;
            // 累加等差数列和
            res += (long long)t * (a[i] + a[i] - (t - 1) * b[i]) / 2;
        } else {
            t = m;
            m = 0;
            // 累加等差数列和
            res += (long long)t * (a[i] + a[i] - (t - 1) * b[i]) / 2;
            break;
        }
    }

    // 如果选出的数的个数小于等于x的个数，将x乘以剩余的个数累加到结果中
    res = res + (long long)(m < cc) * x * m;
    printf("%lld\n", res);
    return 0;
}