Maximize Distance to Closest Person

In a row of seats, 1 represents a person sitting in that seat, and 0 represents that the seat is empty.

There is at least one empty seat, and at least one person sitting.

Alex wants to sit in the seat such that the distance between him and the closest person to him is maximized.

Return that maximum distance to closest person.

Example 1:

Input: [1,0,0,0,1,0,1]
Output: 2
Explanation: 
If Alex sits in the second open seat (seats[2]), then the closest person has distance 2.
If Alex sits in any other open seat, the closest person has distance 1.
Thus, the maximum distance to the closest person is 2.

思路：brute force，O(N^2)，求每个0，的左右两边的最小值，总体求最大值；但是这题最优解是O(N), 双指针，用left表示左边的1，i只要是0就move on，否则update maxdis = (i - left) / 2; 最后还要判断两个特殊的点，如果left = -1 update (i)，和最后A[A.length -1] = 0，走穿了，update(A.length - 1 - left);

class Solution {
    public int maxDistToClosest(int[] seats) {
        if(seats == null || seats.length == 0) {
            return 0;
        }
        int left = -1; 
        int maxdis = Integer.MIN_VALUE;
        for(int i = 0;  i < seats.length; i++) {
            if(seats[i] == 0) {
                continue;
            }
            if(left == -1) {
                maxdis = Math.max(maxdis, i);
            } else {
                // left != -1;
                maxdis = Math.max(maxdis, (i - left) / 2);
            }
            left = i;
        }
        
        if(seats[seats.length - 1] == 0) {
            maxdis = Math.max(maxdis, seats.length - 1 - left);
        }
        return maxdis;
    }
}

来源：CSDN

作者：flyatcmu

链接：https://blog.csdn.net/u013325815/article/details/104296071

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