LeetCode 1184. Distance between bus stops -- vector clockwise and counterclockwise

LeetCode 1184. The distance between bus stops —vector Clockwise and counterclockwise .

Title address : https://leetcode.cn/problems/distance-between-bus-stops/

Problem solving ：

class Solution {
    
public:
    int distanceBetweenBusStops(vector<int>& distance, int start, int destination) {
    
        int result_clockwise=0, result_counterclockwise=0;
        int size=distance.size();
        for(int i=0;(start+i)%size!=destination;++i)
                result_clockwise+=distance[(start+i)%size];

        for(int i=0;(destination+i)%size!=start;++i)
                result_counterclockwise+=distance[(destination+i)%size];
        return min(result_clockwise,result_counterclockwise);
    }
};

Topic notes

The key point of the topic is to give a vector, A start and end , Calculate the cumulative sum respectively , Take the minimum . How to put vector The index is divided into two parts by the following statement ：

(start+i)%n
(destination+i)%n

One accumulates from the beginning , Then on vector Size redundancy of , Until we reach the end . One Accumulate from the end , Also on the vector Size redundancy of , Until we reach the starting point . This remainder is very clever to put a vector Divided into two parts , Whether the end point is greater than the starting point , And greater than vector When it comes to the size of , Will automatically index to the front .