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最新推荐文章于 2020-12-11 18:00:35 发布

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最新推荐文章于 2020-12-11 18:00:35 发布

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原文链接：http://www.cnblogs.com/YCuangWhen/p/5292568.html

本文介绍了一种使用STL-vector实现路径遍历的方法，并通过离散化宽搜算法来计算由路径围成的矩形面积总和。文章提供了一个具体的代码示例，展示了如何利用vector进行高效的数据管理和遍历。

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题意:

　　一个人在一张大图上走,给你路径与起点,求他走出的矩形面积并.(大概这个意思自行百度标题...

SOL:

　　与其说这是一道图论题不如说是一道生动活泼的STL-vector教学....

　　离散化宽搜,没什么别的...vector用得淋漓尽致...

Code:

/*==========================================================================
# Last modified: 2016-03-18 08:32
# Filename: t1.cpp
# Description:
==========================================================================*/
#define me AcrossTheSky
#include <cstdio>
#include <ctime>
#include <string>
#include <cstring>
#include <cstdlib>
#include <iostream>
#include <algorithm>
   
#include <set>
#include <map>
#include <stack>
#include <queue>
#include <vector>
#include <deque>
 
#define lowbit(x) (x)&(-x)
#define FOR(i,a,b) for((i)=(a);(i)<=(b);(i)++)
#define FORP(i,a,b) for(int i=(a);i<=(b);i++)
#define FORM(i,a,b) for(int i=(a);i>=(b);i--)
#define ls(a,b) (((a)+(b)) << 1)
#define rs(a,b) (((a)+(b)) >> 1)
#define getlc(a) ch[(a)][0]
#define getrc(a) ch[(a)][1]
#define pb push_back
#define find(a,b) lower_bound((a).begin(), (a).end(), (b))-(a).begin()
 
#define INF 10000000000
#define maxn 3000
#define maxm 100000
#define pi 3.1415926535898
#define _e 2.718281828459 
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
template<class T> inline
void read(T& num) {
    bool start=false,neg=false;
    char c;
    num=0;
    while((c=getchar())!=EOF) {
        if(c=='-') start=neg=true;
        else if(c>='0' && c<='9') {
            start=true;
            num=num*10+c-'0';
        } else if(start) break;
    }
    if(neg) num=-num;
}
/*==================split line==================*/
ll n, x[maxn], x1 = INF/2, y1 = INF/2, ans = 0;
char d[maxn];
vector<ll> x2,y2;
int a[maxn][maxn];
int dx[4]={-1,0,1,0},dy[4]={0,-1,0,1};
 
void check(){
    FORP(i,0,x2.size()-1) printf("%lld ",x2[i]);
    printf("\n");
    FORP(i,0,y2.size()-1) printf("%lld ",y2[i]);
    cout << endl;
}
void mark(int ld,int rd,int lu,int ru) {
    if (ld>lu) swap(ld,lu); if (rd>ru) swap(rd,ru);
    for (int i=ld;i<=lu;i++)
        for (int j=rd;j<=ru;j++) a[i][j] = 1;
}
queue<int> qx,qy;
void bfs() {
    qx.push(0); qy.push(0);
    while (!qx.empty()){
        int nx=qx.front(),ny=qy.front();
        qx.pop(); qy.pop();
        FORP(i,0,3) {
            int xx=nx+dx[i],yy=ny+dy[i];
            if (xx<0||xx>=x2.size()||yy<0||yy>=y2.size()||a[xx][yy])
            continue;
            else {
                a[xx][yy]=2;
                qx.push(xx); qy.push(yy);
            }
        }
    }
    //FORP(i,0,3) dfs(xx+dx[i],yy+dy[i]);
}
void init(){
    read(n);
    x2.pb(0); x2.pb(INF);
    y2.pb(0); y2.pb(INF);
    FORP(i,0,n-1){
        x2.pb(x1); x2.pb(x1+1);
        y2.pb(y1); y2.pb(y1+1);
        cin >> d[i]; read(x[i]);
        if (d[i]=='R')x1+=x[i];if (d[i]=='L')x1-=x[i];
        if (d[i]=='U')y1+=x[i];if (d[i]=='D')y1-=x[i];
    }
    x2.pb(x1); x2.pb(x1+1);
    y2.pb(y1); y2.pb(y1+1);
   // check();
    sort(x2.begin(), x2.end()); sort(y2.begin(), y2.end());
    x2.erase(unique(x2.begin(),x2.end()),x2.end());
    y2.erase(unique(y2.begin(),y2.end()),y2.end());
     
   // check();
}
int main(){
    //freopen("a.in","r",stdin);
    init();
     
    int xnow=find(x2,INF/2),ynow=find(y2,INF/2);
    ll xx=INF/2, yy=INF/2;
    FORP(i,0,n-1){
        int x4=xnow,y4=ynow;
        if (d[i]=='R') xx+=x[i];if (d[i]=='L') xx-=x[i];
        if (d[i]=='U') yy+=x[i];if (d[i]=='D') yy-=x[i];
        xnow=find(x2,xx); ynow=find(y2,yy);
        mark(xnow, ynow, x4, y4);
    }
    bfs();
 
    FORP(i,0,x2.size()-1)
        FORP(j,0,y2.size()-1)
            if (a[i][j]!=2) ans+=(x2[i+1]-x2[i])*(y2[j+1]-y2[j]);
    printf("%lld\n",ans);
    return 0;
}

转载于:https://www.cnblogs.com/YCuangWhen/p/5292568.html