uva 10181 15-Puzzle Problem

huicpc0860 — Fri, 04 Mar 2011 02:00:00 GMT

#include <stdio.h>
#include <stdlib.h>
#include <algorithm>
using namespace std;
int a[16], k, p;
char path[100];
char ch[] = {'L', 'U', 'D', 'R'};
int dir[] = {-1, -4, 4, 1};
int m[16][16] = {0};
bool go[][4] = {
    0, 0, 1, 1,
    1, 0, 1, 1,
    1, 0, 1, 1,
    1, 0, 1, 0,
    0, 1, 1, 1,
    1, 1, 1, 1,
    1, 1, 1, 1,
    1, 1, 1, 0,
    0, 1, 1, 1,
    1, 1, 1, 1,
    1, 1, 1, 1,
    1, 1, 1, 0,
    0, 1, 0, 1,
    1, 1, 0, 1,
    1, 1, 0, 1,
    1, 1, 0, 0,
};

struct point {
    int x, y;

    bool operator<(const point & p)const {
        return x < p.x;
    }
};

void swap(int i) {
    a[p] = a[p + dir[i]];
    a[p += dir[i]] = 0;
}

bool dfs(int step, int mht, int x) {
    if (mht == 0) {
        path[step] = 0;
        puts(path);
        return 1;
    }
    int cnt = 0;
    point c[4];
    for (int i = 0; i < 4; i++) {
        if (!go[p][i] || i == x)continue;
        int t = p + dir[i];
        c[cnt].x = mht + m[p][a[t] - 1] - m[t][a[t] - 1];
        if (c[cnt].x + step <= k)c[cnt++].y = i;
    }
    sort(c, c + cnt);
    for (int i = 0; i < cnt; i++) {
        path[step] = ch[c[i].y];
        swap(c[i].y);
        if (dfs(step + 1, c[i].x, 3 - c[i].y))return 1;
        swap(3 - c[i].y);
    }
    return 0;
}

int main() {
    for (int i = 0; i < 16; i++)
        for (int j = i + 1; j < 16; j++)
            m[i][j] = m[j][i] = abs(i / 4 - j / 4) + abs(i % 4 - j % 4);
    int T;
    scanf("%d", &T);
    while (T--) {
        int cnt = 0;
        for (int i = 0; i < 16; i++) {
            scanf("%d", &a[i]);
            if (a[i] == 0)p = i;
            for (int j = 0; j < i; j++)
                cnt += a[j] > a[i];
        }
        if (((cnt + m[p][15])&1) == 0)
            puts("This puzzle is not solvable.");
        else {
            int mht = 0;
            for (int i = 0; i < 16; i++)
                if (a[i]) mht += m[i][a[i] - 1];
            for (k = mht; k < 51 && !dfs(0, mht, -1); k++);
        }
    }
    return 0;
}

huicpc0860 2011-03-04 10:00 发表评论

poj 1011 Sticks

huicpc0860 — Mon, 21 Jun 2010 14:38:00 GMT

//搜索入门
#include <stdio.h>
#include <algorithm>
using namespace std;
int length,a[64],n,sum;
bool ok,v[64]={0};
void dfs(int i,int size,int step){
    if(size==length)i=0,size=0,step--;
    if(step==0)ok=1;
    for(int old=-1;!ok&&i<n;i++)
        if(!v[i]&&a[i]!=old&&(size+a[i])<=length){
            v[i]=1;
            old=a[i];
            dfs(i+1,size+a[i],step);
            v[i]=0;
            if(size==0)return;
        }
}
bool cmp(int x,int y){return x>y;}
int main(){
    while(scanf("%d",&n),n){
        sum=0,ok=0;
        for(int i=0;i<n;i++){scanf("%d",&a[i]);sum+=a[i];}
        sort(a,a+n,cmp);
        for(length=a[0];!ok&&length<=sum;length++)
            if(sum%length==0){
                dfs(0,0,(sum/length)-1);
                if(ok)printf("%d\n",length);
            }
    }
    return 0;
}

C++博客-huicpc0860-随笔分类-Searching

uva 10181 15-Puzzle Problem

poj 1011 Sticks