Function st_mincut_value 

pub fn st_mincut_value(
    graph: &Graph,
    source: VertexId,
    target: VertexId,
    capacity: Option<&[f64]>,
) -> IgraphResult<f64>

Scalar s-t minimum-cut value (capacity of the minimum edge set whose removal disconnects source from target).

Counterpart of igraph_st_mincut_value in references/igraph/src/flow/flow.c:1127. By the max-flow / min-cut theorem (Ford-Fulkerson, 1956) the value returned equals max_flow_value; this function is a thin wrapper that exists for naming parity with igraph C and to make call sites intent-revealing when the caller wants the cut interpretation rather than the flow one.

Arguments

• graph — input graph (directed or undirected).
• source — source vertex id (0 ≤ source < vcount()).
• target — sink vertex id (0 ≤ target < vcount(), target != source).
• capacity — optional per-edge capacity in the graph’s edge-id order. When None, each edge contributes unit capacity. When Some(c), c.len() must equal graph.ecount(), and every entry must be finite and ≥ 0.

Returns

The minimum s-t cut capacity as f64. Returns 0.0 when no source → target path exists in the residual network (the empty cut already disconnects them).

Errors

Same as max_flow_value:

• IgraphError::VertexOutOfRange if source or target is outside [0, vcount()).
• IgraphError::InvalidArgument if source == target, the capacity slice length differs from ecount(), or any capacity is negative / non-finite.

Examples

use rust_igraph::{Graph, st_mincut_value};

// Two parallel paths of capacity 1 each → min s-t cut = 2
// (must cut both bottleneck edges to disconnect 0 from 3).
let mut g = Graph::new(4, true).unwrap();
g.add_edge(0, 1).unwrap();
g.add_edge(1, 3).unwrap();
g.add_edge(0, 2).unwrap();
g.add_edge(2, 3).unwrap();
let cap = vec![1.0, 1.0, 1.0, 1.0];
let cut = st_mincut_value(&g, 0, 3, Some(&cap)).unwrap();
assert!((cut - 2.0).abs() < 1e-12);