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// 1579. Remove Max Number of Edges to Keep Graph Fully Traversable
#include "leetcode.h"
/*
* alice and bob have an undirected graph of 'n' nodes and three
* types of edges:
* type1: can be traversed by alice only
* type2: can be traversed by bob only
* type3: can be traversed by both alice and bob
* given an array of 'edges' where 'edges{i} = {typei, ui, vi}'
* represents a bidirectional edge of type 'typei' between nodes
* 'ui' and 'vi', find the maximum number of edges you can remove
* so that after removing the edges, the graph can still be fully
* traversed by alice and bob if starting from any node, they can
* reach all other nodes. return the maximum number of edges you
* can remove, or return -1 if alice and bob cannot traverse graph
*/
int find(int *n, int target) {
return n[target] < 0 ? target : (n[target] = find(n, n[target]));
}
int connect(int *n, int x, int y) {
int a = find(n, x), b = find(n, y);
if (a == b)
return 0;
if (n[a] > n[b])
n[a] = b;
else if (n[b] > n[a])
n[b] = a;
else {
n[a] = b;
n[b]--;
}
return 1;
}
int maxNumEdgesToRemove(int n, int **edges, int edgesSize, int *edgesColSize) {
int e = 0, f = 0, g = 0, b = n, c = n, d = n;
int *p = (int *)malloc(n * sizeof(*p));
int *q = (int *)malloc(n * sizeof(*q));
int *r = (int *)malloc(n * sizeof(*r));
for (int i = 0; i < n; ++i)
p[i] = q[i] = r[i] = -1;
for (int i = 0; i < edgesSize; i++) {
int t = edges[i][0], u = edges[i][1] - 1, v = edges[i][2] - 1;
if (t != 1) {
e++;
b -= connect(p, u, v);
}
if (t != 2) {
f++;
d -= connect(q, u, v);
}
if (t == 3) {
g++;
d -= connect(r, u, v);
}
}
free(p), free(q), free(r);
return b > 1 || c > 1 ? -1 : e + f - g + b + c - d - n;
}
int main() {
int e1[6][3] = {{3, 1, 2}, {3, 2, 3}, {1, 1, 3},
{1, 2, 4}, {1, 1, 2}, {2, 3, 4}};
int e2[4][3] = {{3, 1, 2}, {3, 2, 3}, {1, 1, 4}, {2, 1, 4}};
int e3[3][3] = {{3, 2, 3}, {1, 1, 2}, {2, 3, 4}};
int ecs1[] = {6, 6, 6}, ecs2[] = {4, 4, 4}, ecs3[] = {3, 3, 3};
printf("%d\n", maxNumEdgesToRemove(4, (int **)e1, ARRAY_SIZE(e1),
(int *)ARRAY_SIZE(e1[0]))); // expect: 2
printf("%d\n", maxNumEdgesToRemove(4, (int **)e2, ARRAY_SIZE(e2),
(int *)ARRAY_SIZE(e2[0]))); // expect: 0
printf("%d\n", maxNumEdgesToRemove(4, (int **)e3, ARRAY_SIZE(e3),
(int *)ARRAY_SIZE(e3[0]))); // expect: -1
}
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