Codeforces 946a,b,c

• 2018-03-14
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· Codeforces 946a

Origin：http://codeforces.com/problemset/problem/946/A

题意：正数的和减去负数的和

#include <bits/stdc++.h>
using namespace std;

int main()
{
    int n, ans = 0, t;
    scanf("%d", &n);
    for(int i = 0; i < n; i++)
    {
        scanf("%d", &t);
        ans += abs(t);
    }
    printf("%d\n", ans);

    return 0;
}

· Codeforces 946b

Origin：http://codeforces.com/problemset/problem/946/B

题意：给出a, b，按如下步骤操作

1. If a = 0 or b = 0, end the process. Otherwise, go to step 2;
2. If a ≥ 2·b, then set the value of a to a - 2·b, and repeat step 1. Otherwise, go to step 3;
3. If b ≥ 2·a, then set the value of b to b - 2·a, and repeat step 1. Otherwise, end the process.

最后输出a和b的结果

#include <bits/stdc++.h>
using namespace std;

int main()
{
    long long a, b, t;
    scanf("%lld%lld", &a, &b);
    while(1)
    {
        if (a == 0 || b == 0 || a < 2 * b && b < 2 * a) break;
        a = a % (2 * b);
        if (a == 0 || b < 2 * a) break;
        b = b % (2 * a);
    }
    printf("%lld %lld\n", a, b);

    return 0;
}

· Codeforces 946c

Origin：http://codeforces.com/problemset/problem/946/C

题意：给出一个字符串。每次变换中，字符串中每个字符都可以变为它的下一个字符（比如a变为b，m变为n），也可以不变。不限变换次数。要求在最后的字符串中，”abcdefg…wxyz”是它的子串，问能否做到。若能做到输出最后的字符串，若不能，输出”-1″。

#include <bits/stdc++.h>
using namespace std;

int main()
{
    char s[100005];
    scanf("%s", s);
    int len = strlen(s), pos = 0;
    char ch = 'a';
    for (int i = 0; i < len; i++) { if (ch == 'z' + 1) break; if (s[i] > ch) continue;
        s[i] = ch++;
    }
    if (ch == 'z' + 1) printf("%s\n", s);
    else printf("-1\n");

    return 0;
}