题解 | #坠落的蚂蚁#

#include <algorithm>
#include <cstdio>
#include <vector>
#include <iostream>
using namespace std;
const int MAX = 100 ;
struct P{
    int pos;
    int v;
} a[MAX];

bool cmp(P p1, P p2){
    return p1.pos < p2.pos;
}
/**

图解：
https://blog.nowcoder.net/n/ef050f9ef47945c693c7cca6dbcd4b6e

*/
int main() {
    int n;
    int A;
    cin >> n;
    vector<P> pl;
    vector<P> pr;
    for (int i = 0; i < n; i ++) {
        scanf("%d%d", &a[i].pos, &a[i].v);
        if(a[i].v == 0)
            A = i;
    }
    for(int i = 0; i < n; i ++){
        if (a[i].pos < a[A].pos && a[i].v > 0) {
            pl.push_back(a[i]);
        }else if(a[i].pos > a[A].pos && a[i].v < 0){
            pr.push_back(a[i]);
        }
    }
    if (pl.size() == pr.size()) {
        cout << "Cannot fall!" << endl;
    }else{
        sort(pl.begin(), pl.end(), cmp);
        sort(pr.begin(), pr.end(), cmp);
        if (pl.size() > pr.size()) {
            cout << 100 - pl[pl.size() - pr.size() - 1].pos << endl;//99的时候还没掉下去，故还需要再走1步
        }else{
            cout << pr[pl.size()].pos << endl;
        }
    }
    return 0;
}
// 64 位输出请用 printf("%lld")