全wa了

魂逝_秦月歌 @ 2023-09-11 13:28:50

#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <iomanip>
#include <iostream>
#include <algorithm>
#include <set>
#include <map>
#include <vector>
#include <cctype>
#include <queue>
#include <deque>
#include <ctime>
#include <cstring>
#include <string>
#define _e putchar (' ')
#define _v putchar ('\n')
#define ll long long
#define INF 999999999999999999ll
#define INE -999999999999999999ll
#define File(a) freopen(a".in","r",stdin),freopen(a".out","w",stdout)
using namespace std;
inline int lowbit (int x) {
    return x&(-x);
}
inline int mx(int x,int y) {
    return x>y?x:y;
}
inline int mn(int x,int y) {
    return x<y?x:y;
}
inline void rd(int &x) {
    int s=0,w=1;
    char ch=getchar ();
    while(ch<'0'||ch>'9') {if(ch=='-') w=-1; ch=getchar ();}
    while(ch>='0'&&ch<='9') {s=(s<<1)+(s<<3)+(ch^48); ch=getchar ();}
    x=s*w;
}
inline void wr(int x) {
    if(x<0) x=-x,putchar (45);
    if(x<10) {
        putchar (x+48);
        return ;
    }
    wr(x/10);
    putchar (x%10+48);
}
inline int ab (int x) {
    if(x<0) return -x;
    return x;
}
inline void swap (int &x,int &y) {
    x^=y^=x^=y;
}
const int N=1000005;
int n,m,k,mid,a[N]; 
inline bool check (int x) {
    if (a[x]<k) return 1;
    return 0;
}
inline int binary_search () {
    int lt=0,rt=n;
    while (lt<rt) {
        mid=(lt+rt)>>1;
        if (check (mid)) lt=mid+1;
        else rt=mid;
    }
    if(a[mid+1]==k) return (mid+1);
    else return -1;
}
int main () {
    rd(n),rd(m);
    for (int i=1;i<=n;i++) rd(a[i]);
    sort(a+1,a+1+n);
    for (int j=1;j<=m;j++) {
        rd(k);
        wr(binary_search()),_e;

    }
    return 0;
}

by zacharyzhong @ 2023-09-11 13:34:58

大佬思路没看懂，给个弱智的方法

#include<bits/stdc++.h>
using namespace std;
int n,m,a[1000009];
int main()
{
    cin>>n>>m;
    for(int i=1;i<=n;i++)
        cin>>a[i];
    for(int i=1,x;i<=m;i++)
    {
        cin>>x;
        int p=lower_bound(a+1,a+n+1,x)-a;
        if(a[p]!=x)
            cout<<"-1 ";
        else cout<<p<<' ';
    }
    return 0;
}

by fengyongrui @ 2023-09-14 19:39:48

1.将62行

int lt=0,rt=n;

改为：

int lt=1,rt=n;

2.将68行

if(a[mid+1]==k) return (mid+1);

改为：

if(a[lt]==k) return lt;

更改后代码：

#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <iomanip>
#include <iostream>
#include <algorithm>
#include <set>
#include <map>
#include <vector>
#include <cctype>
#include <queue>
#include <deque>
#include <ctime>
#include <cstring>
#include <string>
#define _e putchar (' ')
#define _v putchar ('\n')
#define ll long long
#define INF 999999999999999999ll
#define INE -999999999999999999ll
#define File(a) freopen(a".in","r",stdin),freopen(a".out","w",stdout)
using namespace std;
inline int lowbit (int x) {
    return x&(-x);
}
inline int mx(int x,int y) {
    return x>y?x:y;
}
inline int mn(int x,int y) {
    return x<y?x:y;
}
inline void rd(int &x) {
    int s=0,w=1;
    char ch=getchar ();
    while(ch<'0'||ch>'9') {if(ch=='-') w=-1; ch=getchar ();}
    while(ch>='0'&&ch<='9') {s=(s<<1)+(s<<3)+(ch^48); ch=getchar ();}
    x=s*w;
}
inline void wr(int x) {
    if(x<0) x=-x,putchar (45);
    if(x<10) {
        putchar (x+48);
        return ;
    }
    wr(x/10);
    putchar (x%10+48);
}
inline int ab (int x) {
    if(x<0) return -x;
    return x;
}
inline void swap (int &x,int &y) {
    x^=y^=x^=y;
}
const int N=1000005;
int n,m,k,mid,a[N]; 
inline bool check (int x) {
    if (a[x]<k) return 1;
    return 0;
}
inline int binary_search () {
    int lt=1,rt=n;//改动1
    while (lt<rt) {
        mid=(lt+rt)>>1;
        if (check (mid)) lt=mid+1;
        else rt=mid;
    }
    if(a[lt]==k) return lt;//改动2
    else return -1;
}
int main () {
    rd(n),rd(m);
    for (int i=1;i<=n;i++) rd(a[i]);
    sort(a+1,a+1+n);
    for (int j=1;j<=m;j++) {
        rd(k);
        wr(binary_search()),_e;

    }
    return 0;
}

by 魂逝_秦月歌 @ 2023-10-08 09:33:33

okok感谢，我三年没碰了都忘了