PTA-21期末基本功训练（二）题解

int IsAutomorphic(int x) {
    unsigned long long s = (unsigned long long) x * x;
    int temp = x;
    int bit = 1;
    while (temp != 0) {
        temp /= 10;
        bit *= 10;
    }
    return (s % bit) == x;
}

int countAlpha(const char *s) {
    int result = 0;
    for (int i = 0; s[i] != '\0'; ++i) {
        if (isalpha(s[i])) ++result;
    }
    return result;
}

int main() {
    int n;
    scanf("%d", &n);
    int result = 0;
    int plus = 1;
    int amount = 0;
    int level = 1;
    for (int i = 0; i != n; ++i) {
        result += plus;
        if (++amount == level) {
            amount = 0;
            ++plus;
            ++level;
        }
    }
    printf("%d", result);
    return 0;
}

int main() {
    int amount[1001] = {0};
    int score[100000];
    int n;
    scanf("%d", &n);
    for (int i = 0; i != n; ++i) {
        scanf("%d", &score[i]);
        ++amount[score[i]];
    }
    int sum[1001] = {0};
    for (int i = 1; i != 1001; ++i) {
        sum[i] = sum[i - 1] + amount[i - 1];
    }
    for (int i = 0; i != n; ++i) {
        printf("%d ", sum[score[i]]);
    }
    return 0;
}

int main() {
    int input;
    bool start = false;
    while (~scanf("%d", &input)) {
        if (start) printf("\n");
        else start = true;
        int d = (input >> 24) & 0xff;
        int c = (input >> 16) & 0xff;
        int b = (input >> 8) & 0xff;
        int a = input & 0xff;
        printf("%d", a + b + c + d);
    }
    return 0;
}

int main() {
    int n, a, b, c, p, q, r;
    scanf("%d %d %d %d %d %d %d", &n, &a, &b, &c, &p, &q, &r);
    printf("%d", n - a - b - c + p + q + r);
    return 0;
}

int main() {
    double x, a;
    scanf("%lf%lf", &x, &a);
    double result = a / x;
    int temp = (int) result;
    if (fabs(result - temp) < 1e-5) printf("%d", temp);
    else printf("%d", temp + 1);
    return 0;
}

int num[1000000];
int sumBefore[1000000];
int sumAfter[1000000];
int record[100000];

int main() {
    int n;
    scanf("%d", &n);
    for (int i = 0; i != n; ++i) {
        scanf("%d", &num[i]);
        if (i == 0) {
            sumBefore[0] = 1;
            record[num[i]] = 1;
        } else if (record[num[i]] == 0) {
            sumBefore[i] = sumBefore[i - 1] + 1;
            record[num[i]] = 1;
        } else sumBefore[i] = sumBefore[i - 1];
    }
    sumAfter[n - 1] = 1;
    memset(record, 0, sizeof(record));
    record[num[n - 1]] = 1;
    for (int i = n - 2; i != -1; --i) {
        if (record[num[i]] == 0) {
            sumAfter[i] = sumAfter[i + 1] + 1;
            record[num[i]] = 1;
        } else {
            sumAfter[i] = sumAfter[i + 1];
        }
    }
    int max = 0;
    for (int i = 1; i != n; ++i) {
        int temp = sumBefore[i - 1] + sumAfter[i];
        if (temp > max) max = temp;
    }
    printf("%d", max);
    return 0;
}

int main() {
    int n;
    scanf("%d", &n);
    int s = 1;
    for (int line = 1; line != n; ++line) {
        int space = n - line;
        for (int i = 0; i != space; ++i) printf(" ");
        printf("*");
        if (line != 1) {
            for (int i = 0; i != s; ++i) printf(" ");
            printf("*");
            s += 2;
        }
        printf("\n");
    }
    for (int i = (n == 1 ? s - 1 : -2); i != s; ++i) printf("*");
    return 0;
}

// 二分查找
// 参数：
//   num[] - 源数组
//   length - 数组的大小
//   key - 要查找的值
// 返回值：
//   如果找到指定的数，那么返回其在数组中的下标
//   如果数组中不包含指定的数，那么返回-(插入点 + 1)
// 插入点：
//   数组中第一个大于key的元素的下标
int binarySearch(int num[], int length, int key) {
    int low = 0;
    int high = length - 1;
    while (low <= high) {
        int mid = (low + high) >> 1;
        int cmp = num[mid] - key;
        if (cmp < 0)
            low = mid + 1;
        else if (cmp > 0)
            high = mid - 1;
        else
            return mid; // key found
    }
    return -(low + 1);  // key not found.
}

int main() {
    int n, m, x, temp;
    scanf("%d %d %d", &n, &m, &x);
    int A[n];
    for (int i = 0; i != n; ++i) scanf("%d", &A[i]);
    for (int i = 0; i != m; ++i) {
        scanf("%d", &temp);
        int key = x - temp;
        int index = binarySearch(A, n, key);
        if (index >= 0) {
            printf("%d %d", index, i);
            break;
        }
    }
    return 0;
}