1010. Lehmer Code (35)解题报告

思路

同PAT TOP 1009一样，都是用树状数组解决，只不过这一题要用到离散化。

通过画面

代码

#define _CRT_SECURE_NO_WARNINGS
#include 
#include 
#define lowbit(x) ((x)&(-x))
const int maxn = static_cast(1e5 + 10);
int c[maxn], n;
void update(int x, int v);
int getSum(int x);
int cmp(const void *v1, const void *v2);
struct num {
	int origin, index;
};

int main(void) {
	int i, *b;
	num *arr;
	bool flag = false;
	setvbuf(stdin, new char[1 << 20], _IOFBF, 1 << 20);
	scanf("%d", &n);
	arr = (num *)calloc(n + 1, sizeof(num));
	b = (int *)calloc(n + 1, sizeof(int));
	for (i = 1; i <= n; i++) {
		scanf("%d", &arr[i].origin);
		arr[i].index = i;
	}
	qsort(arr + 1, n, sizeof(num), cmp);
	for (i = 1; i <= n; i++) {
		b[arr[i].index] = i;
	}
	for (i = 1; i <= n; i++) {
		update(b[i], 1);
		printf("%s%d", flag ? " " : "", b[i] - 1 - getSum(b[i] - 1));
		flag = true;
	}
	delete[] arr;
	delete[] b;
	return 0;
}

void update(int x, int v) {
	int i;
	for (i = x; i <= n; i += lowbit(i)) {
		c[i] += v;
	}
	return;
}

int getSum(int x) {
	int i, sum = 0;
	for (i = x; i > 0; i -= lowbit(i)) {
		sum += c[i];
	}
	return sum;
}

int cmp(const void *v1, const void *v2) {
	num *n1, *n2;
	n1 = (num *)v1;
	n2 = (num *)v2;
	return n1->origin - n2->origin;
}