A. The Doors

代碼：

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

const int maxn = 2e5 + 10;
int N;
int Zero = 0, One = 0;
int a[maxn], b[maxn], suma[maxn], sumb[maxn];
int num1, num2, ans;

int main() {
    scanf("%d", &N);
    for(int i = 0; i < N; i ++) {
        scanf("%d
 
", &a[i]);
        if(a[i] == 1) {
            b[i] = 0;
            One ++;
        }
        if(a[i] == 0) {
            b[i] = 1;
            Zero ++;
        }
        if(i == 0) suma[i] = a[i], sumb[i] = b[i];
        else suma[i] = suma[i - 1] + a[i], sumb[i] = sumb[i - 1] + b[i];
    }

    
 
for(int i = 0; i < N; i ++) {
        if(suma[i] == One) {
            num1 = i;
            break;
        }
    }
    for(int i = 0; i < N; i ++) {
        if(sumb[i] == Zero) {
            num2 = i;
            break;
        }
    }

    ans = min(num1, num2);
    printf("%d\n"
 
, ans + 1);

    return 0;
}

B. Nirvana

代碼：

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

int N;

int Ans(int x) {
    if(x < 10) return max(1, x);
    return max((x % 10) * Ans(x / 10), 9 * Ans(x / 10 - 1));
}

int main() {
    scanf("%d", &N);
    printf("%d\n", Ans(N));
    return 0;
}

C. Queen

代碼：

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

const int maxn = 1e5 + 10;
const int inf = 0x3f3f3f3f;
int N;
int root;
int vis[maxn];
vector<int> ans;

int main() {
    scanf("%d", &N);
    for(int i = 1; i <= N; i ++) {
        int st, col;
        scanf("%d%d", &st, &col);
        if(col == 0) {
            if(st != -1)
                vis[st] = 1;
            vis[i] = 1;
        }
    }

    for(int i = 1; i <= N; i ++) {
        if(vis[i] != 1)
            ans.push_back(i);
    }

    if(ans.size() == 0) printf("-1\n");
    else {
        sort(ans.begin(), ans.end());
        for(int i = 0; i < ans.size(); i ++)
            printf("%d%s", ans[i], i != ans.size() - 1 ? " " : "\n");
    }

    return 0;
}

最近是理解能力下降？？？讀題讀不清楚？？？菜是原罪！！！

CodeForces Round #549 Div.2