UVA 1156 - Pixel Shuffle(模拟+置换)

UVA 1156 - Pixel Shuffle

题目链接

题意：根据题目中的变换方式，给定一串变换方式，问需要执行几次才能回复原图像

思路：这题恶心的一比，先模拟求出一次变换后的对应的矩阵，然后对该矩阵求出所有循环长度，所有循环长度的公倍数就是答案

代码：

#include <stdio.h>#include <string.h>const int N = 1100;int t, n, g[N][N], vis[N][N], save[N][N];char str[N], s[N];void rot(int flag) {for (int i = 0; i < n; i++) {for (int j = 0; j < n; j++) {if (!flag)save[i][j] = g[n - j - 1][i];  else  save[n - j - 1][i] = g[i][j];    } } for (int i = 0; i < n; i++) for (int j = 0; j < n; j++) g[i][j] = save[i][j];}void sym(int flag) {for (int i = 0; i < n; i++) {for (int j = 0; j < n; j++) {save[i][j] = g[i][n - j - 1];  } } for (int i = 0; i < n; i++) for (int j = 0; j < n; j++) g[i][j] = save[i][j];}void bhsym(int flag) {for (int i = 0; i < n / 2; i++) {for (int j = 0; j < n; j++)save[i][j] = g[i][j]; } for (int i = n / 2; i < n; i++) for (int j = 0; j < n; j++) save[i][j] = g[i][n - j - 1]; for (int i = 0; i < n; i++) for (int j = 0; j < n; j++) g[i][j] = save[i][j];}void bvsym(int flag) {for (int i = 0; i < n; i++) { for (int j = 0; j < n; j++) { if (i < n / 2)  save[i][j] = g[i][j];else save[i][j] = g[3 * n / 2 - 1 - i][j];} } for (int i = 0; i < n; i++) for (int j = 0; j < n; j++) g[i][j] = save[i][j];}void div(int flag) {for (int i = 0; i < n; i++) {for (int j = 0; j < n; j++) {if (!flag) {if (i % 2) save[i][j] = g[i / 2 + n / 2][j];else save[i][j] = g[i / 2][j];}else {if (i % 2) save[i / 2 + n / 2][j] = g[i][j];else save[i / 2][j] = g[i][j];   }  } } for (int i = 0; i < n; i++) for (int j = 0; j < n; j++) g[i][j] = save[i][j];}void mix(int flag) {for (int i = 0; i < n; i++){for (int j = 0; j < n; j++){if (i % 2 == 0){if (flag) {if (j % 2 == 0) save[i][j] = g[i][j / 2];else save[i][j] = g[i + 1][j / 2];}else {if (j % 2 == 0) save[i][j / 2] = g[i][j];else save[i + 1][j / 2] = g[i][j];    }}else{if (flag) {if(j % 2 == 0) save[i][j] = g[i - 1][n / 2 + j / 2];else save[i][j] = g[i][n / 2 + j / 2];}else {if(j % 2 == 0) save[i - 1][n / 2 + j / 2] = g[i][j];else save[i][n / 2 + j / 2] = g[i][j];    }}}}for (int i = 0; i < n; i++) for (int j = 0; j < n; j++) g[i][j] = save[i][j];}void change(char *str) {int len = strlen(str);int flag = 1; if (str[0] == '-') { flag = 0; str++; }if (strcmp(str, "tor") == 0) rot(flag);else if (strcmp(str, "mys") == 0) sym(flag);else if (strcmp(str, "myshb") == 0) bhsym(flag);else if (strcmp(str, "mysvb") == 0) bvsym(flag);else if (strcmp(str, "vid") == 0) div(flag);else if (strcmp(str, "xim") == 0) mix(flag);}void tra() {int len = strlen(str); int sn = 0; for (int i = len - 1; i >= 0; i--) {if (str[i] == ' ') {  s[sn] = '\0';change(s);sn = 0;  }  else {  s[sn++] = str[i];    } } s[sn] = '\0'; change(s);}int gcd(int a, int b) {if (!b) return a;return gcd(b, a % b);}int lcm(int a, int b) {return a / gcd(a, b) * b;}int solve() {int ans = 1;memset(vis, 0, sizeof(vis));for (int i = 0; i < n; i++) {for (int j = 0; j < n; j++) {if (!vis[i][j]) {vis[i][j] = 1;int cnt = 1;    int x = g[i][j] / n;int y = g[i][j] % n;while (!vis[x][y]) {cnt++;vis[x][y] = 1;int t = g[x][y] / n;y = g[x][y] % n;x = t;    }    ans = lcm(ans, cnt);   }  } } return ans;}void init() {scanf("%d", &n);getchar();gets(str);for (int i = 0; i < n; i++) {for (int j = 0; j < n; j++) {g[i][j] = i * n + j;  } }}int main() {scanf("%d", &t);while (t--) {init();tra();printf("%d\n", solve());if (t) printf("\n"); }return 0;}