[Princeton Algorithm I] Programming Assignment 1: Percolation（带权并查集）

题目链接：http://coursera.cs.princeton.edu/algs4/assignments/percolation.html

题意：比较繁琐，就是说从第1行到第n行有没有一个连通块能连起来。复习考研码力变弱了太多，这题调了2h。带权并查集，行号越小权值越高就行了。

使用方法：windows下编译运行，按住一个键不放。

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <conio.h>
#include <time.h>

const int dx[5] = {0, 0, 1, -1};
const int dy[5] = {1, -1, 0, 0};

static struct RandomGen {
    RandomGen() { srand((int)time(NULL)); }
    static int getRandom() { return (int)rand()*(int)rand()+(int)rand(); }
}RandomGen;

typedef struct Percolation {
    int* pre;
    int** _G;
    int n, m;

    Percolation() {}
    Percolation(int _n, int _m) : n(_n), m(_m) {
        int _size = _n * _m;
        pre = (int*)malloc(_size*sizeof(int));
        _G = (int**)malloc(_n*sizeof(int*));
        for(int i = 0; i < _size; i++) {
            pre[i] = i;
        }
        for(int i = 0; i < n; i++) {
            _G[i] = (int*)malloc(_m*sizeof(int));
            for(int j = 0; j < m; j++) {
                _G[i][j] = 0;
            }
        }
    }

    int find(int x) {
        return x == pre[x] ? x : pre[x] = find(pre[x]);
    }

    void unite(int x, int y) {
        x = find(x), y = find(y);
        if(x > y) pre[x] = y;
        else pre[y] = x;
    }

    inline int getId(int x, int y) { return x * m + y; }
    inline int ok(int x, int y) { return x >= 0 && y >= 0 && x < n && y < m; }

    inline void update(int x, int y) {
        _G[x][y] = 1;
        for(int i = 0; i < 4; i++) {
            int xx = x + dx[i], yy = y + dy[i];
            if(!ok(xx, yy) || !_G[xx][yy]) continue;
            unite(getId(x, y), getId(xx, yy));
        }
    }
}Percolation;

typedef struct PrintControl {
    Percolation* perc;

    PrintControl() {}
    PrintControl(Percolation* _p) : perc(_p) {}
    
    inline char sign(int x, int y) {
        int id = perc->getId(x, y);
        if(perc->_G[x][y]) {
            if(perc->find(id) / perc->m == 0) return 'O';
            else return '.';
        }
        else return 'X';
    }

    void Print() {
        system("cls");
        for(int i = 0; i < perc->n; i++) {
            for(int j = 0; j < perc->m; j++) {
                printf("%c", sign(i, j));
            }
            printf("
");
        }
        printf("
");
    }
}PrintControl;

typedef struct Simulator {
    int n, m, initSize;
    Percolation perc;
    PrintControl pc;

    Simulator() {}
    Simulator(int _n, int _m, int _i) : n(_n), m(_m), initSize(_i) {
        perc = Percolation(n, m);
        pc = PrintControl(&perc);
        while(_i--) update();
    }

    void update() {
        int x = RandomGen::getRandom() % n,
              y = RandomGen::getRandom() % m;
        perc.update(x, y);
    }
    
    void Semaphore() {
        update();
        pc.Print();
        getch();
    }
}Simulator;

signed main() {
    // freopen("out", "w", stdout);
    Simulator sim(20, 20, 5);
    sim.pc.Print();
    while(1) {
        sim.Semaphore();
    }
    return 0;
}