mininum_in_sorted_array.cc

class Solution {
public:
    /**
     * @param nums: a rotated sorted array
     * @return: the minimum number in the array
     */
    int findMin(vector<int> &nums) {
        int n = nums.size();
        int start = 0, end = n - 1;
        if (nums[start] < nums[end]) return nums[start];
        while (start + 1 < end) {
            int mid = start + (end - start) / 2;
            if (nums[start] < nums[mid]) {
                // start ~ end increase
                start = mid;
            } else if (nums[mid] < nums[end]) {
                // start ~ mid not sure 
                // mid ~ end increase
                end = mid;
            } else {
                // start > mid, mid > end, not possible
            }
        }
        // mid is start or mid is end
        if (nums[start] < nums[end]) {
            return nums[start];
        } else {
            return nums[end];
        }
    }
};