ACM-PKU

  PKU 题号1004，题目Financial Management

  求12个浮点数的平均数，比较水的题目。注意打印的时候，“%.2f”C语言自动完成四舍五入了。

  #include<stdio.h>#define ONLINEvoid online(){#ifdef ONLINE#elsefreopen("Financial.in", "r", stdin);freopen("Financial.out", "w", stdout);#endif}int main(){online();float sum = 0.000;float month = 0.000;for (int i = 0; i < 12; i ++){scanf("%f", &month);sum += month;}sum = sum / 12;printf("$%.2f", sum);return 0;} 

   题号：1005，题目I Think I Need a Houseboat

   以原点为中心的半圆进行腐蚀，每年的腐蚀面积为50平米，问点P能够支撑多少年不被腐蚀到。可以计算以原点O到P为半径的半圆的面积，然后除以50每年，即得到年数，取整+1，也是水题。

#include <stdio.h>#define ONLINEvoid online(){#ifdef ONLINE#elsefreopen("houseboat.in","r", stdin);freopen("houseboat.out", "w", stdout);#endif}int n;float x, y;const float PI = 3.1415926;int main(){online();scanf("%d", &n);for (int i=1; i <= n; i ++){scanf("%f%f", &x, &y);float year = (x * x + y * y) * PI / 100;printf("Property %d: This property will begin eroding in year %d./n", i, (int)year + 1);}printf("END OF OUTPUT./n");return 0;} 

   题号：1006，题目Biorhythms

   这道题要好好说说，具体可以看解题报告，http://zi-jin.com/archives/52，写的很好，但是有个地方理解错了。具体可以看，中国剩余定理http://mba.shengwushibie.com/itbook/BookChapter.asp?id=17863

#include <stdio.h>//#define ONLINEvoid online(){#ifdef ONLINE#elsefreopen("bio.in", "r", stdin);freopen("bio.out", "w", stdout);#endif}const int m[3] = {23, 28, 33};int _gcd, t;void gcd(int a, int b, int &x, int &y){if (!b){x = 1;y = 0;_gcd = a;return;}gcd(b, a % b, x, y);t = x;x = y;y = t - a / b * y;}int solve(int r[], int k, int &M){//m[i]同文中的m_i//k同文中的k，本题是定值3,但其他题目中可能是变量int i, M_i, x, y, a = 0;for (i = 0, M = 1; i < k; M *= m[i++]);for (i = 0; i < k; ++i){M_i = M / m[i];//求逆的过程gcd(m[i], M_i, x, y);a = (a + y * M_i * r[i]) % M;}return (a + M) % M; //保证a非负}int main(){online();int r[3], d=0, c = 1, ans, M;while (scanf("%d%d%d%d", &r[0], &r[1], &r[2], &d) != EOF && r[0] != -1){r[0] %= m[0];r[1] %= m[1];r[2] %= m[2];ans = solve(r, 3, M);while (ans <= d)ans += M;printf("Case %d: the next triple peak occurs in %d days./n", c, ans - d);++c;}}