ZOJ5593:Let's Chat（双指针）

传送门

题意

给出x个a区间和y个b区间，询问a和b交区间的子区间长度为m的个数

分析

类似于双指针，具体见代码

trick

代码

#include <bits/stdc++.h>
using namespace std;

#define F(i,a,b) for(int i=a;i<=b;++i)
#define R(i,a,b) for(int i=a;i<b;++i)
#define mem(a,b) memset(a,b,sizeof(a))
#pragma comment(linker, "/STACK:102400000,102400000")
inline void read(int &x){x=0; char ch=getchar();while(ch<'0') ch=getchar();while(ch>='0'){x=x*10+ch-48; ch=getchar();}}

struct node
{
    int l,r;
}a[101],b[101];
int t,n,m,x,y;
int loca,locb;
int ans;

int main()
{
    for(scanf("%d",&t);t--;)
    {
        scanf("%d %d %d %d",&n,&m,&x,&y);
        for(int i=1;i<=x;++i) scanf("%d %d",&a[i].l,&a[i].r);
        for(int i=1;i<=y;++i) scanf("%d %d",&b[i].l,&b[i].r);
        ans=0;locb=1;
        for(int i=1;i<=x;++i)
        {
            if(locb>y) break;
            if(a[i].r<b[locb].l) continue;
            while(a[i].l>b[locb].r) locb++;
            while(locb<=y&&b[locb].l<=a[i].r)
            {
                int rr=min(b[locb].r,a[i].r),ll=max(b[locb].l,a[i].l);
                if(rr-ll+1>=m) ans+=(rr-ll+2-m);
                if(b[locb].l>=a[i].l&&b[locb].r>=a[i].r) break;
                if(b[locb].l<=a[i].l&&b[locb].r<=a[i].r) {locb++;continue;}
                if(b[locb].l>=a[i].l&&b[locb].r<=a[i].r) {locb++;continue;}
                if(b[locb].l<=a[i].l&&b[locb].r>=a[i].r) break;
                locb++;
            }
        }
        printf("%d
",ans);
    }
    return 0;
}

#include <iostream>
#include <cstdio>
#include <cstring>
#include <vector>;
using namespace std;

struct  points
{
	int l,r;
};
vector <points> a,b;
int main()
{
	int cases,n,m,x,y,i,j,s;
	points now;
	bool flag;
	int m1,m2;
    scanf("%d",&cases);
    while (cases--)
    {
    	scanf("%d%d%d%d",&n,&m,&x,&y);
    	a.clear(); b.clear();
    	for (i=1;i<=x;i++)
    	{
    		scanf("%d%d",&now.l,&now.r);
    		if (now.r-now.l+1>=m)
    		{
    			a.push_back(now);
    		}
    	}
    	for (i=1;i<=y;i++)
    	{
    		scanf("%d%d",&now.l,&now.r);
    		if (now.r-now.l+1>=m)
    		{
    			b.push_back(now);
    		}
    	}
    	if (a.size()==0 || b.size()==0) printf("0
");
    	else
    	{
    		m1=0; m2=0; flag=true; s=0;
    		while (m1<a.size() && m2<b.size())
    		{
    			while (flag && a[m1].r<b[m2].l )
    			{
    				m1++;
    				if (m1==a.size()) {flag=false; break;}
    			}
    			while (flag && b[m2].r<a[m1].l )
    			{
    				m2++;
    				if (m2==b.size()) {flag=false; break;}
    			}
    			if (flag)
    			{
    				x=max(a[m1].l,b[m2].l);
    				y=min(a[m1].r,b[m2].r);
    				if (y-x+1>=m) s+=(y-x+1-m+1);
    				if (a[m1].r<b[m2].r) m1++;
    					else if (a[m1].r>b[m2].r) m2++;
    						else {m1++; m2++; }
    			}
    		}
    		printf("%d
",s);
    	}
    }
    return 0;
}