Beam Search (k=4)

function beamPathfind(grid, start, end, allowDiag, hFn) {
  const h = hFn || HEURISTICS.manhattan;
  const beamWidth = 4;
  let beam = [{
    r: start[0],
    c: start[1]
  }];
  const visited = new Set([key(start[0], start[1])]);
  const prev = new Map();
  while (beam.length) {
    const candidates = [];
    for (const node of beam) {
      visitNode(node.r, node.c);
      if (node.r === end[0] && node.c === end[1]) {
        reconstructPath(prev, start, end);
        return;
      }
      for (const [nr, nc] of getNeighbors(grid, node.r, node.c, allowDiag)) {
        const neighborKey = key(nr, nc);
        if (visited.has(neighborKey)) continue;
        visited.add(neighborKey);
        prev.set(neighborKey, [node.r, node.c]);
        candidates.push({
          r: nr,
          c: nc,
          f: h(nr, nc, end[0], end[1])
        });
        pushFrontier(nr, nc);
      }
    }
    sortByField(candidates, "f");
    beam = candidates.slice(0, beamWidth);
  }
  reportNoPath();
}

def beamPathfind(grid, start, end, allowDiag, hFn):
    h = (hFn or HEURISTICS.manhattan)
    beamWidth = 4
    beam = [{r: start[0], c: start[1]}]
    visited = Set([key(start[0], start[1])])
    prev = Map()
    while beam.length:
        candidates = []
        for node in beam:
            visitNode(node.r, node.c)
            if ((node.r == end[0]) and (node.c == end[1])):
                reconstructPath(prev, start, end)
                return
            for nr, nc in getNeighbors(grid, node.r, node.c, allowDiag):
                neighborKey = key(nr, nc)
                if visited.has(neighborKey):
                    continue
                visited.add(neighborKey)
                prev.set(neighborKey, [node.r, node.c])
                candidates.push({r: nr, c: nc, f: h(nr, nc, end[0], end[1])})
                pushFrontier(nr, nc)
        sortByField(candidates, "f")
        beam = candidates[0:beamWidth]
    reportNoPath()

#include <vector>
#include <algorithm>
void beamPathfind(int grid, int start, int end, int allowDiag, int hFn) {
    auto h = (hFn || HEURISTICS.manhattan);
    auto beamWidth = 4;
    auto beam = [{r: start[0], c: start[1]}];
    auto visited = Set([key(start[0], start[1])]);
    auto prev = Map();
    while(beam.length) {
        auto candidates = [];
        /* for-of not directly supported */
        sortByField(candidates, "f");
        beam = candidates[0:beamWidth];
    }
    reportNoPath();
}

public void beamPathfind(int grid, int start, int end, int allowDiag, int hFn) {
    var h = (hFn || HEURISTICS.manhattan);
    var beamWidth = 4;
    var beam = [{r: start[0], c: start[1]}];
    var visited = Set([key(start[0], start[1])]);
    var prev = Map();
    while(beam.length) {
        var candidates = [];
        /* for-of not directly supported */
        sortByField(candidates, "f");
        beam = candidates[0:beamWidth];
    }
    reportNoPath();
}

#include <stdio.h>
void beamPathfind(int grid, int start, int end, int allowDiag, int hFn) {
    var h = (hFn || HEURISTICS.manhattan);
    var beamWidth = 4;
    var beam = [{r: start[0], c: start[1]}];
    var visited = Set([key(start[0], start[1])]);
    var prev = Map();
    while(beam.length) {
        var candidates = [];
        /* for-of not directly supported in C */
        sortByField(candidates, "f");
        beam = candidates[0:beamWidth];
    }
    reportNoPath();
}