Leetcode#34 Search for a Range

原题地址

二分搜索变种

代码：

vector<int> searchRange(int A[], int n, int target) {
        vector<int> range(2, -1);
        int l, r;
        
        // left
        l = 0;
        r = n - 1;
        while (l <= r) {
            int m = (l + r) / 2;
            if (A[m] < target)
                l = m + 1;
            else
                r = m - 1;
        }
        if (l < n && A[l] == target)
            range[0] = l;
        
        // right
        l = 0;
        r = n - 1;
        while (l <= r) {
            int m = (l + r) / 2;
            if (A[m] > target)
                r = m - 1;
            else
                l = m + 1;
        }
        if (r >= 0 && A[r] == target)
            range[1] = r;
            
        return range;
}