NYOJ298 点的变换 【矩阵乘法经典】

  1 //题目链接 http://acm.nyist.edu.cn/JudgeOnline/problem.php?pid=298
  2 #include <cstdio>
  3 #include <iostream>
  4 #include <algorithm>
  5 #include <cstring>
  6 #include <cmath>
  7 #define LL long long
  8 using namespace std;
  9 const int MAXN = 5;
 10 const int MAXS = 1e4+2;
 11 const double pi = acos(-1.0);
 12 int N, M;
 13 
 14 struct mat
 15 {
 16     double m[MAXN][MAXN];
 17 }base;
 18 mat pp[MAXS];
 19 
 20 mat muti(mat a, mat b)
 21 {
 22     mat res;
 23     memset(res.m, 0, sizeof(res.m));
 24     for(int i = 1; i <= 3; i++){
 25         for(int j = 1; j <= 3; j++)
 26         if(a.m[i][j]){
 27             for(int k = 1; k <= 3; k++)
 28                 res.m[i][k] = (res.m[i][k] + a.m[i][j] * b.m[j][k]);
 29         }
 30     }
 31     return res;
 32 }
 33 
 34 mat add(mat a, mat b)
 35 {
 36     mat res;
 37     memset(res.m, 0, sizeof(res.m));
 38     for(int i = 1; i <= 3; i++){
 39         for(int j = 1; j <= 3; j++){
 40             res.m[i][j] = (a.m[i][j] + b.m[i][j]);
 41         }
 42     }
 43     return res;
 44 }
 45 
 46 //mat qpow(mat a, int n)
 47 //{
 48 //    mat res;
 49 //    memset(res.m, 0, sizeof(res.m));
 50 //    for(int i = 1; i <= 3; i++) res.m[i][i] = 1;
 51 //
 52 //    while(n){
 53 //        if(n&1) res = muti(res, a);
 54 //        n>>=1;
 55 //        a = myti(a, a);
 56 //    }
 57 //    return res;
 58 //}
 59 
 60 int main()
 61 {
 62     char com;
 63     mat tmp;
 64     double a, b;
 65     scanf("%d %d", &N, &M);
 66     for(int i = 1; i <= N; i++){
 67         scanf("%lf %lf", &a, &b);
 68         pp[i].m[1][1] = a;
 69         pp[i].m[2][1] = b;
 70         pp[i].m[3][1] = 1;
 71     }
 72     memset(tmp.m, 0, sizeof(tmp.m));
 73     for(int i = 1; i <= 3; i++) tmp.m[i][i] = 1;
 74     while(M--){
 75         memset(base.m, 0, sizeof(base.m));
 76         for(int i = 1; i <= 3; i++) base.m[i][i] = 1;
 77         getchar();
 78         scanf("%c", &com);
 79         if(com == ‘M‘){
 80             scanf("%lf %lf", &a, &b);
 81             base.m[1][3] = a;
 82             base.m[2][3] = b;
 83         }
 84         else if(com == ‘X‘){
 85             base.m[2][2] = -1;
 86         }
 87         else if(com == ‘Y‘){
 88             base.m[1][1] = -1;
 89         }
 90         else if(com == ‘S‘){
 91             scanf("%lf", &a);
 92             base.m[1][1] = a;
 93             base.m[2][2] = a;
 94         }
 95         else if(com == ‘R‘){
 96             scanf("%lf", &a);
 97             a = a/180*pi;
 98             base.m[1][1] = cos(a);
 99             base.m[1][2] = -sin(a);
100             base.m[2][1] = sin(a);
101             base.m[2][2] = cos(a);
102         }
103         tmp = muti(base, tmp);
104     }
105     mat ans;
106     for(int i = 1; i <= N; i++){
107 //        pp[i] = muti(tmp, pp[i]);
108 //        printf("%.1f %.1f\n", pp[i].m[1][1], pp[i].m[2][1]);
109         ans = muti(tmp, pp[i]);
110         printf("%.1f %.1f\n", ans.m[1][1], ans.m[2][1]);
111     }
112     return 0;
113 }