[leetcode 153] Find Minimum in Rotated Sorted Array

原创于 2015-01-12 20:21:46 发布 · 266 阅读

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本文介绍如何在已知旋转排序数组中找到最小元素，提供了两种方法：二分查找和线性遍历。二分查找方法通过不断缩小搜索范围来高效定位最小值，而线性遍历则从头开始逐个比较直至找到最小值。

Suppose a sorted array is rotated at some pivot unknown to you beforehand.

(i.e., 0 1 2 4 5 6 7 might become 4 5 6 7 0 1 2).

Find the minimum element.

You may assume no duplicate exists in the array.

二分

class Solution {
public:
    int findMin(vector<int> &num) {
        int r = num.size();
        if (r == 1) {
            return num[0];
        }
        r--;
        int l = 0;
        while (l < r) {
            int mid = l + (r-l)/2;
            if (num[mid] > num[r]) {
                l = mid + 1;
            } else {
                r = mid;
            }
        }
        return num[l];
    }
};

遍历

class Solution {
public:
    int findMin(vector<int> &num) {
        const int n = num.size();
        for (int i = 1; i < n; i++) {
            if (num[i] < num[i-1]) {
                return num[i];
            }
        }
        return num[0];
    }
};