7-53-两个有序序列的中位数-编程题

解题代码

#include<stdio.h>
#include<stdlib.h>
int Re(int a[], int left, int right, int K);
int main()
{
	int num, i, j, left, right, t;
	scanf("%d", &num);
	int *a = (int *)malloc(num * 2 * sizeof(int));
	for (i = 0; i < num * 2; i++) {
		scanf("%d", &a[i]);
	}
	left = 0, right = num * 2 - 1;
	int re = Re(a, left, right, num + 1);
	printf("%d", re);
	return 0;
}
int Re(int a[], int left, int right, int K) {
	int e = a[left];
	int l = left, r = right;
	int t;
	while (l <= r) {
		while (l <= r&&a[l] >= e) l++;
		while (r>=l&&a[r] < e) r--;
		if (l < r) {
			t; t = a[l]; a[l] = a[r]; a[r] = t;
		}
	}
	t = a[l - 1]; a[l - 1] = a[left]; a[left] = t;
	if (l - left - 1 >= K) return Re(a, left, l - 2, K);
	else if (l - left - 1 < K - 1) return Re(a, l, right, K - l + left);
	else return e;
}

测试结果

问题整理

1.注意循环的判断条件。