先记录棋盘，再对棋盘遍历，找出各棋子的位置，避免记录棋子的数量；对黑棋和白棋用不同的遍历顺序，避免对棋子位置排序。贴一下代码：

#include <iostream>
#include <map>
#include <cstring>

using namespace std;

char upper(char c) {
	if (c >= 'a' && c <= 'z') return char(c - 'a' + 'A');
	return c;
}

void display(char board[][8], char c, bool isWhite) {
	char tmp;
	int row;
	for (int i = 0; i < 8; ++i) {
		for (int j = 0; j < 8; ++j) {
			row = isWhite ? 7 - i : i;
			tmp = board[row][j];
			if ( tmp == c) {
				if (c == 'k' || c == 'K') {
					std::cout << upper(c) << char('a' + j) << 8 - row;
				}
				else if (c == 'p' || c == 'P') {
					cout << "," << char('a' + j) << 8 - row;
				}
				else {
					cout << "," << upper(c) << char('a' + j) << 8 - row;
				}
			}
		}
	}
}

int main() {
	char board[8][8]; // (row, col)
	memset(board, 0, sizeof(board));
	char c;
	int cnt = 0;
	char white[] = "KQRBNP";
	char black[] = "kqrbnp";
	do {
		c = getchar();
		if (c == ':' || c == '.') {
			char tmp = getchar();
			if(tmp != c)
				board[cnt / 8][cnt % 8] = tmp;
			cnt++;
			getchar();
		}
	} while (c != EOF);

	cout << "White: ";
	for (int i = 0; i < 6; ++i) {
		display(board, white[i], true);
	}
	cout << endl;

	cout << "Black: ";
	for (int i = 0; i < 6; ++i) {
		display(board, black[i], false);
	}
	cout << endl;

	return 0;
}