URAL 1149 Sinus Dances

URAL_1149

    根据通项公式找到递推式之后就可以递归打印任意的An及Sn了。

#include<stdio.h>
#include<string.h>
int N;
void dfsA(int n, int up)
{
    if(n == 1)
    {
        printf("sin(%d)", up);
        return ;
    }
    printf("sin(%d%c", up - n + 1, (up - n + 1) & 1 ? '-' : '+');
    dfsA(n - 1, up);
    printf(")");
}
void dfsS(int n, int up)
{
    if(n == 1)
    {
        dfsA(1, 1);
        printf("+%d", up);
        return ;
    }
    printf("(");
    dfsS(n - 1, up);
    printf(")");
    dfsA(n, n);
    printf("+%d", up - n + 1);
}
int main()
{
    while(scanf("%d", &N) == 1)
    {
        dfsS(N, N);
        printf("\n");
    }
    return 0;
}