ARST打卡第110周[110/521]

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// The API isBadVersion is defined for you.
// bool isBadVersion(int version);

class Solution {
public:
    int firstBadVersion(int n) {
        // 防止溢出的一般性思路是开大空间
        long long l = 1;
        long long r = n;
        long long mid;
        while (l < r) {
            mid = (l + r) >> 1;
            // 优化思路
            // mid = l + (r - l) >> 1;
            if (isBadVersion(mid)) {
                r = mid;
            } else {
                l = mid + 1;
            }
        }
        return l;
    }
};