#all WA 求助！

P2249 【深基13.例1】查找

xingyu671 @ 2023-07-25 14:50:22

#include<iostream>
#include<cmath>
#include<string>
using namespace std;
int a[1000005];
int main()
{
    int n,m;
    cin >> n >> m;
    for(int i = 1;i <= n;i++)
    {
        cin >> a[i];
    }
    for(int i = 1;i <= m;i++)
    {
        int x,h = n,l = 0,mid;
        cin >> x;
        if(x > a[n] || x < a[1])
        {
            cout << "-1 ";
            continue;
        }
        while(l <= h)
        {
            mid = (l+h)/2;
            if(a[mid] == x)
            {
                cout << mid << ' ';
                break;
            }
            else if(a[mid] > x)
            {
                h = mid-1;
            }
            else
            {
                l = mid+1;
            }
        }
        if(l > h) cout << "-1 ";
    }
   return 0;
}

help!!!!

by eggy_LIKE @ 2024-08-16 11:31:01

#include<bits/stdc++.h>
using namespace std;
int a[1000005], x, n, m;
void solve() {
    cin >> x;  // 输入当前查询的数字
    int l = 1, r = n, ans = -1;  // 初始化二分查找的左右边界和结果
    // 二分查找
    while(l<=r) {
        int mid = l+(r-l)/2;  // 计算中间位置
        if(a[mid] == x) {
            ans = mid;    // 找到目标值
            r = mid-1;  // 缩小右边界
        } else if(a[mid] > x) {
            r = mid-1;  // 缩小右边界
        } else {
            l = mid+1;  // 缩小左边界
        }
    }
    cout << ans << " ";  // 输出结果
}
int main() {
    cin >> n >> m;  // 输入 n 和 m
    for(int i = 1; i <= n; i++) {
        cin >> a[i];  // 输入序列中的 n 个数
    }    
    while(m--) solve(); 
    return 0;
}