Submission #3009670

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Source Code Expand

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

int P[100005];

class DisjointSet {
    public:
        vector<int> rank, p;
    
    DisjointSet() {}
    DisjointSet(int size) {
        rank.resize(size, 0);
        p.resize(size, 0);
        for (int i = 0; i < size; i++) makeSet(i);
    }

    void makeSet(int x) {
        p[x] = x;
        rank[x] = 0;
    }

    bool same(int x, int y) {
        return findSet(x) == findSet(y);
    }

    void unite(int x, int y) {
        link(findSet(x), findSet(y));
    }

    void link(int x, int y) {
        if (rank[x] > rank[y]) {
            p[y] = x;
        } else {
            p[x] = y;
            if (rank[x] == rank[y]) rank[y]++;
        }
    }

    int findSet(int x) {
        if (x != p[x]) {
            p[x] = findSet(p[x]);
        }
        return p[x];
    }
};

int main() {
    int N, M, x, y;
    scanf("%d %d", &N, &M);

    DisjointSet ds = DisjointSet(N+1);

    for (int i = 1; i <= N; i++) scanf("%d", &P[i]);

    for (int i = 1; i <= M; i++) {
        scanf("%d %d", &x, &y);
        ds.unite(x, y);
    }

    int ans = 0;
    for (int i = 1; i <= N; i++) {
        if (P[i] == i) ans++;
        else if (ds.same(i, P[i])) ans++;
    }
    
    printf("%d\n", ans);
    return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:49:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d %d", &N, &M);
                           ^
./Main.cpp:53:52: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
     for (int i = 1; i <= N; i++) scanf("%d", &P[i]);
                                                    ^
./Main.cpp:56:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d %d", &x, &y);
                               ^

Judge Result