Submission #8266997

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Source Code Expand

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

struct UnionFind {
    vector<int> par;
    vector<int> sz;

    UnionFind(int n=0){
        if(n>0) initialize(n);
    }

    void initialize(int n){
        par.resize(n);
        sz.resize(n);
        for(int i=0; i<n; i++){
            par[i] = i;
            sz[i] = 1;
        }
    }

    int find(int x){
        if(par[x] == x){
            return x;
        }else{
            return par[x] = find(par[x]);
        }
    }

    bool unite(int x, int y){
        x = find(x);
        y = find(y);
        if(x == y) return false;
        if(sz[x] > sz[y]) swap(x, y);
        par[x] = y;
        sz[y] += sz[x];
        return true;
    }

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

    int size(int x){
        return sz[find(x)];
    }
};

int main(){
    int N, M, K;
    cin >> N >> M >> K;
    vector<vector<int>> es(M);
    for(int i=0; i<M; i++){
        int a, b, c;
        scanf("%d %d %d", &a, &b, &c);
        es[i] = {c, a-1, b-1, i};
    }
    sort(es.rbegin(), es.rend());

    // 出力しやすいように子供は1-indexedで扱っている
    vector<int> ans(M, 0);
    vector<UnionFind> uf(K+1, N);

    for(auto& e : es){
        int a = e[1], b = e[2], i = e[3];
        // ok側が(a, b)非連結、ng側が既に連結
        int ok = K+1, ng = 0;
        while(ok-ng>1){
            int mid = (ok+ng)/2;
            (uf[mid].same(a, b) ? ng : ok) = mid;
        }
        if(ok != K+1){
            uf[ok].unite(a, b);
            ans[i] = ok;
        }
    }
    for(int a : ans) printf("%d\n", a);
    return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:54:38: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d %d %d", &a, &b, &c);
                                      ^

Judge Result