题目：

题解：

void maxHeapify(int* a, int i, int heapSize) {
    int l = i * 2 + 1, r = i * 2 + 2, largest = i;
    if (l < heapSize && a[l] > a[largest]) {
        largest = l;
    }
    if (r < heapSize && a[r] > a[largest]) {
        largest = r;
    }
    if (largest != i) {
        int t = a[i];
        a[i] = a[largest], a[largest] = t;
        maxHeapify(a, largest, heapSize);
    }
}

void buildMaxHeap(int* a, int heapSize) {
    for (int i = heapSize / 2; i >= 0; --i) {
        maxHeapify(a, i, heapSize);
    }
}

int findKthLargest(int* nums, int numsSize, int k) {
    int heapSize = numsSize;
    buildMaxHeap(nums, heapSize);
    for (int i = numsSize - 1; i >= numsSize - k + 1; --i) {
        int t = nums[0];
        nums[0] = nums[i], nums[i] = t;
        --heapSize;
        maxHeapify(nums, 0, heapSize);
    }
    return nums[0];
}