归并排序算法

class MergeSort {
    public:
    void merge(vector<int>& values, int left, int mid, int right) {
        vector<int> res;
        res.resize(right-left+1);
        int i=left;
        int j=mid+1;
        int k=0;
        while(i<=mid || j<=right) {
            if (i>mid) {
                res[k++] = values[j++];
            } else if (j>right) {
                res[k++] = values[i++];
            } else if (values[i] < values[j]) {
                res[k++] = values[i++];
            } else {
                res[k++] = values[j++];
            }
        }

        i=0;
        for (int k=left; k<=right; ++k) {
            if (i < res.size()) {
                values[k] = res[i++];
            } else {
                break;
            }
        }
    }
    void mergeSort(vector<int>& values, int left, int right) {
        if(left >= right) {
            return;
        }
        int mid = left + (right-left)/2;
        mergeSort(values,left, mid);
        mergeSort(values, mid + 1, right);
        merge(values, left, mid, right);
    }
    void mergeSort(vector<int>& values) {
        mergeSort(values, 0, values.size()-1);
    }
};