Acwing160周赛题解

A

#include <iostream>
#include <algorithm>
#include <cstring>

using namespace std;

int main() {
   
	ios::sync_with_stdio(false);
	cin.tie(0), cout.tie(0);

	int n;
	cin >> n;
	
	int res = 0;
	for (int i = 0; i < n; ++i) {
   
		int val;
		cin >> val;
		if (val > 90 && val < 180) res++;
	}
	
	cout << res << "\n";
	
	return 0;
}

B

极限情况分析最大数$9^{100}$, 因此需要高精度运算

#include <iostream>
#include <algorithm>
#include <cstring>
#include <vector>
#include <cmath>

using namespace std;

const int N = 250;

int n;
char str[N];

bool check() {
   
	for (int i = 0; i < n; ++i) if (str[i] != '0') return false;
	return true;
}

int main() {
   
	ios::sync_with_stdio(false);
	cin.tie(0), cout.tie(0);

	char c;
	vector<int> nums;
	int ptr = 0;

	while (cin >> c, c != 'e') {
   
		if (c == '.') {
   
			ptr = n - 1;
			continue;
		}
		str[n++] = c;
	}
	int val;
	cin >> val;
	ptr += val;

	if (check()) {
   
		cout << 0 << "\n";
		return 0;
	}

	if (n == 2 && str[0] == '1' && str[1] == '0' && ptr == 0) {
   
		cout << 1 << "\n";
		return 0;
	}

	int i = 0;
	if (str[0] == '0' && ptr > 0) i++;
	for (; i < n; ++i) {
   
		cout << str[i];
		if (i == ptr && ptr != n - 1) cout << '.';
	}

	while (ptr >= n) cout << 0, n++;
	return 0;
}

C

计算最大分数以及总分数能被$k+1$整除

#include <iostream>
#include <algorithm>
#include <cstring>

using namespace std;

typedef pair<int, int> PII;
const int N = 110, M = 11, INF = 0x3f3f3f3f;

int n, m, k;
int w[N][N];
int f[N][N][M];
PII fa[N][N][M];

int get(int val) {
   
    return (val % k + k) % k;
}

int main() {
   
    ios::sync_with_stdio(false);
	cin.tie(0), cout.tie(0);

    cin >> n >> m >> k;
    k++;

    for (int i = 1; i <= n; ++i) {
   
        for (int j = 1; j <= m; ++j) {
   
            char c;
			cin >> c;
			w[i][j] = c - '0';
        }
    }

    memset(f, -0x3f, sizeof f);
    for (int i = 1; i <= m; ++i) f[1][i][get(w[1][i])] = w[1][i];

    for (int i = 2; i <= n; ++i) {
   
        for (int j = 1; j <= m; ++j) {
   
            for (int r = 0; r < k; ++r) {
   
                int val1 = -INF, val2 = -INF;
				int tmp = w[i][j];

                if (j - 1 >= 1) val1 = f[i - 1][j - 1][get(r - tmp)];
                if (j + 1 <= m) val2 = f[i - 1][j + 1][get(r - tmp)];
                if (val1 > val2) {
   
					f[i][j][r] = val1 + tmp;
					fa[i][j][r] = {
   i - 1, j - 1};
				}
				else {
   
					f[i][j][r] = val2 + tmp;
					fa[i][j][r] = {
   i - 1, j + 1};
				}
            }
        }
    }

	int res = -INF, r = n, c = 1;
	for (int i = 1; i <= m; ++i) {
   
		if (f[n][i][0] > res) {
   
			res = f[n][i][0];
			c = i;
		}
	}

	if (res < -INF / 2) cout << -1 << "\n";
	else {
   
		cout << res << "\n";
		cout << c << "\n";

		string str;
		int curr = 0;

		while (r >= 1 && c >= 1) {
   
			auto [_r, _c] = fa[r][c][curr];
			if (_c + 1 == c) str += 'L';
			else if (_c - 1 == c) str += 'R';
			curr = get(curr - w[r][c]);
			r = _r, c = _c;
		}

		cout << str << "\n";
	}

	return 0;
}